diff --git a/accessible/src/atk/nsApplicationAccessibleWrap.cpp b/accessible/src/atk/nsApplicationAccessibleWrap.cpp
index 592776054a18..4d059cb70fd7 100644
--- a/accessible/src/atk/nsApplicationAccessibleWrap.cpp
+++ b/accessible/src/atk/nsApplicationAccessibleWrap.cpp
@@ -647,7 +647,8 @@ nsApplicationAccessibleWrap::AddRootAccessible(nsIAccessible *aRootAccWrap)
     AtkObject *atkAccessible = nsAccessibleWrap::GetAtkObject(aRootAccWrap);
     atk_object_set_parent(atkAccessible, mAtkObject);
 
-    PRUint32 count = mChildren.Count();
+    PRUint32 count = 0;
+    mChildren->GetLength(&count);
     g_signal_emit_by_name(mAtkObject, "children_changed::add", count - 1,
                           atkAccessible, NULL);
 
@@ -669,27 +670,36 @@ nsApplicationAccessibleWrap::RemoveRootAccessible(nsIAccessible *aRootAccWrap)
 {
     NS_ENSURE_ARG_POINTER(aRootAccWrap);
 
-    PRInt32 index = mChildren.IndexOf(aRootAccWrap);
+    PRUint32 index = 0;
+    nsresult rv = NS_ERROR_FAILURE;
+
+    // we must use weak ref to get the index
+    nsCOMPtr<nsIWeakReference> weakPtr = do_GetWeakReference(aRootAccWrap);
+    rv = mChildren->IndexOf(0, weakPtr, &index);
 
     AtkObject *atkAccessible = nsAccessibleWrap::GetAtkObject(aRootAccWrap);
     atk_object_set_parent(atkAccessible, NULL);
     g_signal_emit_by_name(mAtkObject, "children_changed::remove", index,
                           atkAccessible, NULL);
 
-    nsresult rv = nsApplicationAccessible::RemoveRootAccessible(aRootAccWrap);
-
 #ifdef MAI_LOGGING
-    PRUint32 count = mChildren.Count();
+    PRUint32 count = 0;
+    mChildren->GetLength(&count);
 
     if (NS_SUCCEEDED(rv)) {
+        rv = mChildren->RemoveElementAt(index);
         MAI_LOG_DEBUG(("\nRemove RootAcc=%p, count=%d\n",
                        (void*)aRootAccWrap, (count-1)));
     }
     else
         MAI_LOG_DEBUG(("\nFail to Remove RootAcc=%p, count=%d\n",
                        (void*)aRootAccWrap, count));
-#endif
+#else
+    NS_ENSURE_SUCCESS(rv, rv);
+    rv = mChildren->RemoveElementAt(index);
 
+#endif
+    InvalidateChildren();
     return rv;
 }
 
diff --git a/accessible/src/base/nsAccessible.cpp b/accessible/src/base/nsAccessible.cpp
index efe0f1e6f08b..6280ef672ab2 100644
--- a/accessible/src/base/nsAccessible.cpp
+++ b/accessible/src/base/nsAccessible.cpp
@@ -149,12 +149,14 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(nsAccessible)
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsAccessible, nsAccessNode)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mParent)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mChildren)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mFirstChild)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mNextSibling)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(nsAccessible, nsAccessNode)
   NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mParent)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMARRAY(mChildren)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mFirstChild)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(mNextSibling)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_ADDREF_INHERITED(nsAccessible, nsAccessNode)
@@ -227,8 +229,8 @@ nsresult nsAccessible::QueryInterface(REFNSIID aIID, void** aInstancePtr)
 }
 
 nsAccessible::nsAccessible(nsIDOMNode* aNode, nsIWeakReference* aShell): nsAccessNodeWrap(aNode, aShell), 
-  mParent(nsnull), mRoleMapEntry(nsnull),
-  mAreChildrenInitialized(PR_FALSE)
+  mParent(nsnull), mFirstChild(nsnull), mNextSibling(nsnull), mRoleMapEntry(nsnull),
+  mAccChildCount(eChildCountUninitialized)
 {
 #ifdef NS_DEBUG_X
    {
@@ -480,9 +482,39 @@ nsAccessible::GetKeyboardShortcut(nsAString& aAccessKey)
   return NS_OK;
 }
 
+void
+nsAccessible::SetParent(nsIAccessible *aParent)
+{
+  if (mParent != aParent) {
+    // Adopt a child -- we allow this now. the new parent
+    // may be a dom node which wasn't previously accessible but now is.
+    // The old parent's children now need to be invalidated, since 
+    // it no longer owns the child, the new parent does
+    nsRefPtr<nsAccessible> oldParent = nsAccUtils::QueryAccessible(mParent);
+    if (oldParent)
+      oldParent->InvalidateChildren();
+  }
+
+  mParent = aParent;
+}
+
+void
+nsAccessible::SetFirstChild(nsIAccessible *aFirstChild)
+{
+  mFirstChild = aFirstChild;
+}
+
+void
+nsAccessible::SetNextSibling(nsIAccessible *aNextSibling)
+{
+  mNextSibling = aNextSibling;
+}
+
 nsresult
 nsAccessible::Shutdown()
 {
+  mNextSibling = nsnull;
+
   // Invalidate the child count and pointers to other accessibles, also make
   // sure none of its children point to this parent
   InvalidateChildren();
@@ -495,112 +527,198 @@ nsAccessible::Shutdown()
   return nsAccessNodeWrap::Shutdown();
 }
 
+void
+nsAccessible::InvalidateChildren()
+{
+  // Document has transformed, reset our invalid children and child count
+
+  // Reset the sibling pointers, they will be set up again the next time
+  // CacheChildren() is called.
+  // Note: we don't want to start creating accessibles at this point,
+  // so don't use GetNextSibling() here. (bug 387252)
+  nsRefPtr<nsAccessible> child = nsAccUtils::QueryAccessible(mFirstChild);
+  while (child) {
+    child->mParent = nsnull;
+
+    nsCOMPtr<nsIAccessible> next = child->mNextSibling;
+    child->mNextSibling = nsnull;
+    child = nsAccUtils::QueryAccessible(next);
+  }
+
+  mAccChildCount = eChildCountUninitialized;
+  mFirstChild = nsnull;
+}
+
 NS_IMETHODIMP
 nsAccessible::GetParent(nsIAccessible **aParent)
 {
-  NS_ENSURE_ARG_POINTER(aParent);
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
 
-  NS_IF_ADDREF(*aParent = GetParent());
-  return *aParent ? NS_OK : NS_ERROR_FAILURE;
+  nsCOMPtr<nsIAccessible> cachedParent = GetCachedParent();
+  if (cachedParent) {
+    cachedParent.swap(*aParent);
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIAccessibleDocument> docAccessible(GetDocAccessible());
+  NS_ENSURE_TRUE(docAccessible, NS_ERROR_FAILURE);
+
+  return docAccessible->GetAccessibleInParentChain(mDOMNode, PR_TRUE, aParent);
+}
+
+already_AddRefed<nsIAccessible>
+nsAccessible::GetCachedParent()
+{
+  if (IsDefunct())
+    return nsnull;
+
+  nsCOMPtr<nsIAccessible> cachedParent = mParent;
+  return cachedParent.forget();
+}
+
+already_AddRefed<nsIAccessible>
+nsAccessible::GetCachedFirstChild()
+{
+  if (IsDefunct())
+    return nsnull;
+
+  nsCOMPtr<nsIAccessible> cachedFirstChild = mFirstChild;
+  return cachedFirstChild.forget();
 }
 
   /* readonly attribute nsIAccessible nextSibling; */
-NS_IMETHODIMP
-nsAccessible::GetNextSibling(nsIAccessible **aNextSibling) 
-{
-  NS_ENSURE_ARG_POINTER(aNextSibling);
+NS_IMETHODIMP nsAccessible::GetNextSibling(nsIAccessible * *aNextSibling) 
+{ 
+  *aNextSibling = nsnull; 
+  if (!mWeakShell) {
+    // This node has been shut down
+    return NS_ERROR_FAILURE;
+  }
+  if (!mParent) {
+    nsCOMPtr<nsIAccessible> parent(GetParent());
+    if (parent) {
+      PRInt32 numChildren;
+      parent->GetChildCount(&numChildren);  // Make sure we cache all of the children
+    }
+  }
 
-  nsresult rv = NS_OK;
-  NS_IF_ADDREF(*aNextSibling = GetSiblingAtOffset(1, &rv));
-  return rv;
+  if (mNextSibling || !mParent) {
+    // If no parent, don't try to calculate a new sibling
+    // It either means we're at the root or shutting down the parent
+    NS_IF_ADDREF(*aNextSibling = mNextSibling);
+
+    return NS_OK;
+  }
+
+  return NS_ERROR_FAILURE;
 }
 
   /* readonly attribute nsIAccessible previousSibling; */
-NS_IMETHODIMP
-nsAccessible::GetPreviousSibling(nsIAccessible * *aPreviousSibling) 
+NS_IMETHODIMP nsAccessible::GetPreviousSibling(nsIAccessible * *aPreviousSibling) 
 {
-  NS_ENSURE_ARG_POINTER(aPreviousSibling);
+  *aPreviousSibling = nsnull;
 
-  nsresult rv = NS_OK;
-  NS_IF_ADDREF(*aPreviousSibling = GetSiblingAtOffset(-1, &rv));
-  return rv;
+  if (!mWeakShell) {
+    // This node has been shut down
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIAccessible> parent;
+  if (NS_FAILED(GetParent(getter_AddRefs(parent))) || !parent) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIAccessible> testAccessible, prevSibling;
+  parent->GetFirstChild(getter_AddRefs(testAccessible));
+  while (testAccessible && this != testAccessible) {
+    prevSibling = testAccessible;
+    prevSibling->GetNextSibling(getter_AddRefs(testAccessible));
+  }
+
+  if (!prevSibling) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ADDREF(*aPreviousSibling = prevSibling);
+  return NS_OK;
 }
 
   /* readonly attribute nsIAccessible firstChild; */
-NS_IMETHODIMP
-nsAccessible::GetFirstChild(nsIAccessible **aFirstChild) 
-{
-  NS_ENSURE_ARG_POINTER(aFirstChild);
-  *aFirstChild = nsnull;
-
-  if (gIsCacheDisabled)
+NS_IMETHODIMP nsAccessible::GetFirstChild(nsIAccessible * *aFirstChild) 
+{  
+  if (gIsCacheDisabled) {
     InvalidateChildren();
+  }
+  PRInt32 numChildren;
+  GetChildCount(&numChildren);  // Make sure we cache all of the children
 
-  PRInt32 childCount = GetChildCount();
-  NS_ENSURE_TRUE(childCount != -1, NS_ERROR_FAILURE);
+#ifdef DEBUG
+  nsRefPtr<nsAccessible> firstChild(nsAccUtils::QueryAccessible(mFirstChild));
+  if (firstChild) {
+    nsCOMPtr<nsIAccessible> realParent = firstChild->GetCachedParent();
+    NS_ASSERTION(!realParent || realParent == this,
+                 "Two accessibles have the same first child accessible.");
+  }
+#endif
 
-  if (childCount > 0)
-    NS_ADDREF(*aFirstChild = GetChildAt(0));
+  NS_IF_ADDREF(*aFirstChild = mFirstChild);
 
-  return NS_OK;
+  return NS_OK;  
 }
 
   /* readonly attribute nsIAccessible lastChild; */
-NS_IMETHODIMP
-nsAccessible::GetLastChild(nsIAccessible **aLastChild)
-{
-  NS_ENSURE_ARG_POINTER(aLastChild);
-  *aLastChild = nsnull;
-
-  PRInt32 childCount = GetChildCount();
-  NS_ENSURE_TRUE(childCount != -1, NS_ERROR_FAILURE);
-
-  NS_IF_ADDREF(*aLastChild = GetChildAt(childCount - 1));
+NS_IMETHODIMP nsAccessible::GetLastChild(nsIAccessible * *aLastChild)
+{  
+  GetChildAt(-1, aLastChild);
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsAccessible::GetChildAt(PRInt32 aChildIndex, nsIAccessible **aChild)
+NS_IMETHODIMP nsAccessible::GetChildAt(PRInt32 aChildNum, nsIAccessible **aChild)
 {
-  NS_ENSURE_ARG_POINTER(aChild);
-  *aChild = nsnull;
+  // aChildNum is a zero-based index
 
-  PRInt32 childCount = GetChildCount();
-  NS_ENSURE_TRUE(childCount != -1, NS_ERROR_FAILURE);
+  PRInt32 numChildren;
+  GetChildCount(&numChildren);
 
-  // If child index is negative, then return last child.
-  // XXX: do we really need this?
-  if (aChildIndex < 0)
-    aChildIndex = childCount - 1;
+  // If no children or aChildNum is larger than numChildren, return null
+  if (aChildNum >= numChildren || numChildren == 0 || !mWeakShell) {
+    *aChild = nsnull;
+    return NS_ERROR_FAILURE;
+  // If aChildNum is less than zero, set aChild to last index
+  } else if (aChildNum < 0) {
+    aChildNum = numChildren - 1;
+  }
 
-  nsIAccessible* child = GetChildAt(aChildIndex);
-  if (!child)
-    return NS_ERROR_INVALID_ARG;
+  nsCOMPtr<nsIAccessible> current(mFirstChild), nextSibling;
+  PRInt32 index = 0;
+
+  while (current) {
+    nextSibling = current;
+    if (++index > aChildNum) {
+      break;
+    }
+    nextSibling->GetNextSibling(getter_AddRefs(current));
+  }
+
+  NS_IF_ADDREF(*aChild = nextSibling);
 
-  NS_ADDREF(*aChild = child);
   return NS_OK;
 }
 
 // readonly attribute nsIArray children;
-NS_IMETHODIMP
-nsAccessible::GetChildren(nsIArray **aOutChildren)
+NS_IMETHODIMP nsAccessible::GetChildren(nsIArray **aOutChildren)
 {
-  NS_ENSURE_ARG_POINTER(aOutChildren);
   *aOutChildren = nsnull;
+  nsCOMPtr<nsIMutableArray> children = do_CreateInstance(NS_ARRAY_CONTRACTID);
+  if (!children)
+    return NS_ERROR_FAILURE;
 
-  PRInt32 childCount = GetChildCount();
-  NS_ENSURE_TRUE(childCount != -1, NS_ERROR_FAILURE);
-
-  nsresult rv = NS_OK;
-  nsCOMPtr<nsIMutableArray> children =
-    do_CreateInstance(NS_ARRAY_CONTRACTID, &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  for (PRInt32 childIdx = 0; childIdx < childCount; childIdx++) {
-    nsIAccessible* child = GetChildAt(childIdx);
-    children->AppendElement(child, PR_FALSE);
+  nsCOMPtr<nsIAccessible> curChild;
+  while (NextChild(curChild)) {
+    children->AppendElement(curChild, PR_FALSE);
   }
-
+  
   NS_ADDREF(*aOutChildren = children);
   return NS_OK;
 }
@@ -617,6 +735,39 @@ nsIAccessible *nsAccessible::NextChild(nsCOMPtr<nsIAccessible>& aAccessible)
   return (aAccessible = nextChild);
 }
 
+void nsAccessible::CacheChildren()
+{
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+
+  if (mAccChildCount == eChildCountUninitialized) {
+    mAccChildCount = 0;// Prevent reentry
+    PRBool allowsAnonChildren = GetAllowsAnonChildAccessibles();
+    nsAccessibleTreeWalker walker(mWeakShell, mDOMNode, allowsAnonChildren);
+    // Seed the frame hint early while we're still on a container node.
+    // This is better than doing the GetPrimaryFrameFor() later on
+    // a text node, because text nodes aren't in the frame map.
+    walker.mState.frame = GetFrame();
+
+    nsRefPtr<nsAccessible> prevAcc;
+    PRInt32 childCount = 0;
+    walker.GetFirstChild();
+    SetFirstChild(walker.mState.accessible);
+
+    while (walker.mState.accessible) {
+      ++ childCount;
+      prevAcc = nsAccUtils::QueryAccessible(walker.mState.accessible);
+      prevAcc->SetParent(this);
+      walker.GetNextSibling();
+      prevAcc->SetNextSibling(walker.mState.accessible);
+    }
+    mAccChildCount = childCount;
+  }
+}
+
 PRBool
 nsAccessible::GetAllowsAnonChildAccessibles()
 {
@@ -624,23 +775,73 @@ nsAccessible::GetAllowsAnonChildAccessibles()
 }
 
 /* readonly attribute long childCount; */
-NS_IMETHODIMP
-nsAccessible::GetChildCount(PRInt32 *aChildCount) 
+NS_IMETHODIMP nsAccessible::GetChildCount(PRInt32 *aAccChildCount) 
 {
-  NS_ENSURE_ARG_POINTER(aChildCount);
-
-  *aChildCount = GetChildCount();
-  return *aChildCount != -1 ? NS_OK : NS_ERROR_FAILURE;  
+  CacheChildren();
+  *aAccChildCount = mAccChildCount;
+  return NS_OK;  
 }
 
 /* readonly attribute long indexInParent; */
-NS_IMETHODIMP
-nsAccessible::GetIndexInParent(PRInt32 *aIndexInParent)
+NS_IMETHODIMP nsAccessible::GetIndexInParent(PRInt32 *aIndexInParent)
 {
-  NS_ENSURE_ARG_POINTER(aIndexInParent);
+  *aIndexInParent = -1;
+  if (!mWeakShell) {
+    return NS_ERROR_FAILURE;
+  }
 
-  *aIndexInParent = GetIndexInParent();
-  return *aIndexInParent != -1 ? NS_OK : NS_ERROR_FAILURE;
+  nsCOMPtr<nsIAccessible> parent;
+  GetParent(getter_AddRefs(parent));
+  if (!parent) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIAccessible> sibling;
+  parent->GetFirstChild(getter_AddRefs(sibling));
+  if (!sibling) {
+    return NS_ERROR_FAILURE;
+  }
+
+  *aIndexInParent = 0;
+  while (sibling != this) {
+    NS_ASSERTION(sibling, "Never ran into the same child that we started from");
+
+    if (!sibling)
+      return NS_ERROR_FAILURE;
+
+    ++*aIndexInParent;
+    nsCOMPtr<nsIAccessible> tempAccessible;
+    sibling->GetNextSibling(getter_AddRefs(tempAccessible));
+    sibling = tempAccessible;
+  }
+
+  return NS_OK;
+}
+
+void
+nsAccessible::TestChildCache(nsIAccessible *aCachedChild)
+{
+#ifdef DEBUG_A11Y
+  // All cached accessible nodes should be in the parent
+  // It will assert if not all the children were created
+  // when they were first cached, and no invalidation
+  // ever corrected parent accessible's child cache.
+  if (mAccChildCount <= 0)
+    return;
+
+  nsCOMPtr<nsIAccessible> sibling = mFirstChild;
+
+  while (sibling != aCachedChild) {
+    NS_ASSERTION(sibling, "[TestChildCache] Never ran into the same child that we started from");
+    if (!sibling)
+      return;
+
+    nsCOMPtr<nsIAccessible> tempAccessible;
+    sibling->GetNextSibling(getter_AddRefs(tempAccessible));
+    sibling = tempAccessible;
+  }
+
+#endif
 }
 
 nsresult nsAccessible::GetTranslatedString(const nsAString& aKey, nsAString& aStringOut)
@@ -2912,247 +3113,8 @@ nsAccessible::GetNameInternal(nsAString& aName)
   return NS_OK;
 }
 
-void
-nsAccessible::SetParent(nsIAccessible *aParent)
-{
-  NS_PRECONDITION(aParent, "This method isn't used to set null parent!");
-
-  if (mParent && mParent != aParent) {
-    // Adopt a child -- we allow this now. the new parent
-    // may be a dom node which wasn't previously accessible but now is.
-    // The old parent's children now need to be invalidated, since 
-    // it no longer owns the child, the new parent does
-    NS_ASSERTION(PR_FALSE, "Adopting child!");
-    nsRefPtr<nsAccessible> oldParent = nsAccUtils::QueryAccessible(mParent);
-    if (oldParent)
-      oldParent->InvalidateChildren();
-  }
-
-  mParent = aParent;
-}
-
-void
-nsAccessible::InvalidateChildren()
-{
-  PRInt32 childCount = mChildren.Count();
-  for (PRInt32 childIdx = 0; childIdx < childCount; childIdx++) {
-    nsRefPtr<nsAccessible> child =
-      nsAccUtils::QueryObject<nsAccessible>(mChildren.ObjectAt(childIdx));
-    child->mParent = nsnull;
-  }
-
-  mChildren.Clear();
-  mAreChildrenInitialized = PR_FALSE;
-}
-
-nsIAccessible*
-nsAccessible::GetParent()
-{
-  if (IsDefunct())
-    return nsnull;
-
-  if (mParent)
-    return mParent;
-
-  nsCOMPtr<nsIAccessibleDocument> docAccessible(GetDocAccessible());
-  NS_ASSERTION(docAccessible, "No document accessible for valid accessible!");
-
-  if (!docAccessible)
-    return nsnull;
-
-  nsCOMPtr<nsIAccessible> parent;
-  docAccessible->GetAccessibleInParentChain(mDOMNode, PR_TRUE,
-                                            getter_AddRefs(parent));
-
-#ifdef DEBUG
-  nsRefPtr<nsAccessible> parentAcc = nsAccUtils::QueryAccessible(parent);
-  NS_ASSERTION(!parentAcc->IsDefunct(), "Defunct parent!");
-
-  parentAcc->EnsureChildren();
-  if (parent != mParent)
-    NS_WARNING("Bad accessible tree!");
-#endif
-
-  return parent;
-}
-
-nsIAccessible*
-nsAccessible::GetChildAt(PRUint32 aIndex)
-{
-  if (EnsureChildren())
-    return nsnull;
-
-  nsIAccessible *child = mChildren.SafeObjectAt(aIndex);
-  if (!child)
-    return nsnull;
-
-#ifdef DEBUG
-  nsRefPtr<nsAccessible> childAcc = nsAccUtils::QueryAccessible(child);
-  nsCOMPtr<nsIAccessible> realParent = childAcc->mParent;
-  NS_ASSERTION(!realParent || realParent == this,
-               "Two accessibles have the same first child accessible!");
-#endif
-
-  return child;
-}
-
-PRInt32
-nsAccessible::GetChildCount()
-{
-  return EnsureChildren() ? -1 : mChildren.Count();
-}
-
-PRInt32
-nsAccessible::GetIndexOf(nsIAccessible *aChild)
-{
-  return EnsureChildren() ? -1 : mChildren.IndexOf(aChild);
-}
-
-PRInt32
-nsAccessible::GetIndexInParent()
-{
-  nsIAccessible *parent = GetParent();
-  if (!parent)
-    return -1;
-
-  nsRefPtr<nsAccessible> parentAcc =
-    nsAccUtils::QueryObject<nsAccessible>(parent);
-  return parentAcc->GetIndexOf(this);
-}
-
-already_AddRefed<nsIAccessible>
-nsAccessible::GetCachedParent()
-{
-  if (IsDefunct())
-    return nsnull;
-
-  nsCOMPtr<nsIAccessible> cachedParent = mParent;
-  return cachedParent.forget();
-}
-
-already_AddRefed<nsIAccessible>
-nsAccessible::GetCachedFirstChild()
-{
-  if (IsDefunct())
-    return nsnull;
-
-  nsCOMPtr<nsIAccessible> cachedFirstChild = GetChildAt(0);
-  return cachedFirstChild.forget();
-}
-
-
 ////////////////////////////////////////////////////////////////////////////////
-// nsAccessible protected methods
-
-void
-nsAccessible::CacheChildren()
-{
-  PRBool allowsAnonChildren = GetAllowsAnonChildAccessibles();
-  nsAccessibleTreeWalker walker(mWeakShell, mDOMNode, allowsAnonChildren);
-
-  // Seed the frame hint early while we're still on a container node.
-  // This is better than doing the GetPrimaryFrameFor() later on
-  // a text node, because text nodes aren't in the frame map.
-  walker.mState.frame = GetFrame();
-
-  walker.GetFirstChild();
-  while (walker.mState.accessible) {
-    mChildren.AppendObject(walker.mState.accessible);
-
-    nsRefPtr<nsAccessible> acc =
-      nsAccUtils::QueryObject<nsAccessible>(walker.mState.accessible);
-    acc->SetParent(this);
-
-    walker.GetNextSibling();
-  }
-}
-
-void
-nsAccessible::TestChildCache(nsIAccessible *aCachedChild)
-{
-#ifdef DEBUG_A11Y
-  // All cached accessible nodes should be in the parent
-  // It will assert if not all the children were created
-  // when they were first cached, and no invalidation
-  // ever corrected parent accessible's child cache.
-  PRUint32 childCount = mChildren.Count();
-  if (childCount == 0) {
-    NS_ASSERTION(mAreChildrenInitialized,
-                 "Children are stored but not initailzied!");
-    return;
-  }
-
-  for (PRInt32 childIdx = 0; childIdx < childCount; childIdx++) {
-    nsIAccessible *child = GetChildAt(childIdx);
-    if (child == aCachedChild)
-      break;
-  }
-
-  NS_ASSERTION(child == aCachedChild,
-               "[TestChildCache] cached accessible wasn't found. Wrong accessible tree!");  
-#endif
-}
-
-PRBool
-nsAccessible::EnsureChildren()
-{
-  if (IsDefunct()) {
-    mAreChildrenInitialized = PR_FALSE;
-    return PR_TRUE;
-  }
-
-  if (mAreChildrenInitialized)
-    return PR_FALSE;
-
-  mAreChildrenInitialized = PR_TRUE; // Prevent reentry
-  CacheChildren();
-
-  return PR_FALSE;
-}
-
-nsIAccessible*
-nsAccessible::GetSiblingAtOffset(PRInt32 aOffset, nsresult* aError)
-{
-  if (IsDefunct()) {
-    if (aError)
-      *aError = NS_ERROR_FAILURE;
-
-    return nsnull;
-  }
-
-  nsIAccessible *parent = GetParent();
-  if (!parent) {
-    if (aError)
-      *aError = NS_ERROR_UNEXPECTED;
-
-    return nsnull;
-  }
-
-  nsRefPtr<nsAccessible> parentAcc =
-    nsAccUtils::QueryObject<nsAccessible>(parent);
-
-  PRInt32 indexInParent = parentAcc->GetIndexOf(this);
-  if (indexInParent == -1) {
-    if (aError)
-      *aError = NS_ERROR_UNEXPECTED;
-
-    return nsnull;
-  }
-
-  if (aError) {
-    PRInt32 childCount = parentAcc->GetChildCount();
-    if (indexInParent + aOffset >= childCount) {
-      *aError = NS_OK; // fail peacefully
-      return nsnull;
-    }
-  }
-
-  nsIAccessible *child = parentAcc->GetChildAt(indexInParent + aOffset);
-  if (aError && !child)
-    *aError = NS_ERROR_UNEXPECTED;
-
-  return child;
-}
+// nsAccessible private methods
 
 already_AddRefed<nsIAccessible>
 nsAccessible::GetFirstAvailableAccessible(nsIDOMNode *aStartNode)
diff --git a/accessible/src/base/nsAccessible.h b/accessible/src/base/nsAccessible.h
index f68c6c3beac7..ee5a49859179 100644
--- a/accessible/src/base/nsAccessible.h
+++ b/accessible/src/base/nsAccessible.h
@@ -103,11 +103,11 @@ private:
 
 
 #define NS_ACCESSIBLE_IMPL_CID                          \
-{  /* 07c5a6d6-4e87-4b57-8613-4c39e1b5150a */           \
-  0x07c5a6d6,                                           \
-  0x4e87,                                               \
-  0x4b57,                                               \
-  { 0x86, 0x13, 0x4c, 0x39, 0xe1, 0xb5, 0x15, 0x0a }    \
+{  /* 53cfa871-be42-47fc-b416-0033653b3151 */           \
+  0x53cfa871,                                           \
+  0xbe42,                                               \
+  0x47fc,                                               \
+  { 0xb4, 0x16, 0x00, 0x33, 0x65, 0x3b, 0x31, 0x51 }    \
 }
 
 class nsAccessible : public nsAccessNodeWrap, 
@@ -199,7 +199,22 @@ public:
                                    nsIAccessible **aChild);
 
   //////////////////////////////////////////////////////////////////////////////
-  // Initializing methods
+  // Initializing and cache methods
+
+  /**
+   * Set accessible parent.
+   */
+  void SetParent(nsIAccessible *aParent);
+
+  /**
+   * Set first accessible child.
+   */
+  void SetFirstChild(nsIAccessible *aFirstChild);
+
+  /**
+   * Set next sibling accessible.
+   */
+  void SetNextSibling(nsIAccessible *aNextSibling);
 
   /**
    * Set the ARIA role map entry for a new accessible.
@@ -211,45 +226,10 @@ public:
   virtual void SetRoleMapEntry(nsRoleMapEntry *aRoleMapEntry);
 
   /**
-   * Set accessible parent.
-   */
-  void SetParent(nsIAccessible *aParent);
-
-  /**
-   * Set the child count to -1 (unknown) and null out cached child pointers.
-   * Should be called when accessible tree is changed because document has
-   * transformed.
+   * Set the child count to -1 (unknown) and null out cached child pointers
    */
   virtual void InvalidateChildren();
 
-  //////////////////////////////////////////////////////////////////////////////
-  // Accessible tree traverse methods
-
-  /**
-   * Return parent accessible.
-   */
-  virtual nsIAccessible* GetParent();
-
-  /**
-   * Return child accessible at the given index.
-   */
-  virtual nsIAccessible* GetChildAt(PRUint32 aIndex);
-
-  /**
-   * Return child accessible count.
-   */
-  virtual PRInt32 GetChildCount();
-
-  /**
-   * Return index of the given child accessible.
-   */
-  virtual PRInt32 GetIndexOf(nsIAccessible *aChild);
-
-  /**
-   * Return index in parent accessible.
-   */
-  PRInt32 GetIndexInParent();
-
   /**
    * Return parent accessible only if cached.
    */
@@ -260,8 +240,13 @@ public:
    */
   already_AddRefed<nsIAccessible> GetCachedFirstChild();
 
+  /**
+   * Assert if child not in parent's cache.
+   */
+  void TestChildCache(nsIAccessible *aCachedChild);
+
   //////////////////////////////////////////////////////////////////////////////
-  // Miscellaneous methods
+  // Miscellaneous methods.
 
   /**
    * Fire accessible event.
@@ -284,41 +269,22 @@ public:
   virtual nsresult AppendTextTo(nsAString& aText, PRUint32 aStartOffset,
                                 PRUint32 aLength);
 
+  //////////////////////////////////////////////////////////////////////////////
+  // Helper methods
+  
+  already_AddRefed<nsIAccessible> GetParent() {
+    nsIAccessible *parent = nsnull;
+    GetParent(&parent);
+    return parent;
+  }
+
 protected:
-
-  //////////////////////////////////////////////////////////////////////////////
-  // Initializing, cache and tree traverse methods
-
-  /**
-   * Cache accessible children.
-   */
-  virtual void CacheChildren();
-
-  /**
-   * Assert if child not in parent's cache.
-   */
-  void TestChildCache(nsIAccessible *aCachedChild);
-
-  /**
-   * Cache children if necessary. Return true if the accessible is defunct.
-   */
-  PRBool EnsureChildren();
-
-  /**
-   * Return sibling accessible at the given offset.
-   */
-  virtual nsIAccessible* GetSiblingAtOffset(PRInt32 aOffset,
-                                            nsresult* aError = nsnull);
-
-  //////////////////////////////////////////////////////////////////////////////
-  // Miscellaneous helpers
-
   virtual nsIFrame* GetBoundsFrame();
   virtual void GetBoundsRect(nsRect& aRect, nsIFrame** aRelativeFrame);
   PRBool IsVisible(PRBool *aIsOffscreen); 
 
   //////////////////////////////////////////////////////////////////////////////
-  // Name helpers
+  // Name helpers.
 
   /**
    * Compute the name of HTML node.
@@ -334,6 +300,25 @@ protected:
   static nsresult GetFullKeyName(const nsAString& aModifierName, const nsAString& aKeyName, nsAString& aStringOut);
   static nsresult GetTranslatedString(const nsAString& aKey, nsAString& aStringOut);
 
+  /**
+   * Walk into subtree and calculate the string which is used as the accessible
+   * name or description.
+   *
+   * @param aContent      [in] traversed content
+   * @param aFlatString   [in, out] result string
+   * @param aIsRootHidden [in] specifies whether root content (we started to
+   *                      traverse from) is hidden, in this case the result
+   *                      string is calculated from hidden children
+   *                      (this is used when hidden root content is explicitly
+   *                      specified as label or description by author)
+   */
+  nsresult AppendFlatStringFromSubtreeRecurse(nsIContent *aContent,
+                                              nsAString *aFlatString,
+                                              PRBool aIsRootHidden);
+
+  // Helpers for dealing with children
+  virtual void CacheChildren();
+  
   // nsCOMPtr<>& is useful here, because getter_AddRefs() nulls the comptr's value, and NextChild
   // depends on the passed-in comptr being null or already set to a child (finding the next sibling).
   nsIAccessible *NextChild(nsCOMPtr<nsIAccessible>& aAccessible);
@@ -451,10 +436,11 @@ protected:
 
   // Data Members
   nsCOMPtr<nsIAccessible> mParent;
-  nsCOMArray<nsIAccessible> mChildren;
-  PRBool mAreChildrenInitialized;
+  nsCOMPtr<nsIAccessible> mFirstChild;
+  nsCOMPtr<nsIAccessible> mNextSibling;
 
   nsRoleMapEntry *mRoleMapEntry; // Non-null indicates author-supplied role; possibly state & value as well
+  PRInt32 mAccChildCount;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsAccessible,
diff --git a/accessible/src/base/nsApplicationAccessible.cpp b/accessible/src/base/nsApplicationAccessible.cpp
index e2ec604f5fff..2af2b4e99678 100644
--- a/accessible/src/base/nsApplicationAccessible.cpp
+++ b/accessible/src/base/nsApplicationAccessible.cpp
@@ -42,22 +42,64 @@
  
 #include "nsApplicationAccessible.h"
 
-#include "nsAccessibilityService.h"
-
 #include "nsIComponentManager.h"
 #include "nsServiceManagerUtils.h"
 
-nsApplicationAccessible::nsApplicationAccessible() :
-  nsAccessibleWrap(nsnull, nsnull)
+nsApplicationAccessible::nsApplicationAccessible():
+    nsAccessibleWrap(nsnull, nsnull), mChildren(nsnull)
 {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // nsISupports
 
-NS_IMPL_ISUPPORTS_INHERITED0(nsApplicationAccessible, nsAccessible)
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsApplicationAccessible)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsApplicationAccessible,
+                                                  nsAccessible)
+
+  nsCOMPtr<nsISimpleEnumerator> enumerator;
+  tmp->mChildren->Enumerate(getter_AddRefs(enumerator));
+
+  nsCOMPtr<nsIWeakReference> childWeakRef;
+  nsCOMPtr<nsIAccessible> accessible;
+
+  PRBool hasMoreElements;
+  while(NS_SUCCEEDED(enumerator->HasMoreElements(&hasMoreElements))
+        && hasMoreElements) {
+
+    enumerator->GetNext(getter_AddRefs(childWeakRef));
+    accessible = do_QueryReferent(childWeakRef);
+    if (accessible) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "nsApplicationAccessible child");
+      cb.NoteXPCOMChild(accessible);
+    }
+  }
+  
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(nsApplicationAccessible,
+                                                nsAccessible)
+  tmp->mChildren->Clear();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(nsApplicationAccessible)
+NS_INTERFACE_MAP_END_INHERITING(nsAccessible)
+
+NS_IMPL_ADDREF_INHERITED(nsApplicationAccessible, nsAccessible)
+NS_IMPL_RELEASE_INHERITED(nsApplicationAccessible, nsAccessible)
 
 ////////////////////////////////////////////////////////////////////////////////
+// nsIAccessNode
+
+nsresult
+nsApplicationAccessible::Init()
+{
+  nsresult rv;
+  mChildren = do_CreateInstance(NS_ARRAY_CONTRACTID, &rv);
+  return rv;
+}
+
 // nsIAccessible
 
 NS_IMETHODIMP
@@ -88,67 +130,19 @@ nsApplicationAccessible::GetName(nsAString& aName)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsApplicationAccessible::GetDescription(nsAString& aValue)
+nsresult
+nsApplicationAccessible::GetRoleInternal(PRUint32 *aRole)
 {
-  aValue.Truncate();
+  *aRole = nsIAccessibleRole::ROLE_APP_ROOT;
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsApplicationAccessible::GetRole(PRUint32 *aRole)
 {
-  NS_ENSURE_ARG_POINTER(aRole);
-
   return GetRoleInternal(aRole);
 }
 
-NS_IMETHODIMP
-nsApplicationAccessible::GetState(PRUint32 *aState, PRUint32 *aExtraState)
-{
-  NS_ENSURE_ARG_POINTER(aState);
-  *aState = 0;
-
-  if (aExtraState)
-    *aExtraState = 0;
-
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-nsApplicationAccessible::GetParent(nsIAccessible **aAccessible)
-{
-  NS_ENSURE_ARG_POINTER(aAccessible);
-  *aAccessible = nsnull;
-
-  return IsDefunct() ? NS_ERROR_FAILURE : NS_OK;
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessNode public methods
-
-PRBool
-nsApplicationAccessible::IsDefunct()
-{
-  return nsAccessibilityService::gIsShutdown;
-}
-
-nsresult
-nsApplicationAccessible::Init()
-{
-  return NS_OK;
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessible public methods
-
-nsresult
-nsApplicationAccessible::GetRoleInternal(PRUint32 *aRole)
-{
-  *aRole = nsIAccessibleRole::ROLE_APP_ROOT;
-  return NS_OK;
-}
-
 nsresult
 nsApplicationAccessible::GetStateInternal(PRUint32 *aState,
                                           PRUint32 *aExtraState)
@@ -160,59 +154,124 @@ nsApplicationAccessible::GetStateInternal(PRUint32 *aState,
   return NS_OK;
 }
 
-nsIAccessible*
-nsApplicationAccessible::GetParent()
+NS_IMETHODIMP
+nsApplicationAccessible::GetParent(nsIAccessible **aParent)
 {
-  return nsnull;
+  *aParent = nsnull;
+  return NS_OK;
 }
 
-void
-nsApplicationAccessible::InvalidateChildren()
+NS_IMETHODIMP
+nsApplicationAccessible::GetChildAt(PRInt32 aChildNum, nsIAccessible **aChild)
 {
-  // Do nothing because application children are kept updated by
-  // AddRootAccessible() and RemoveRootAccessible() method calls.
+  NS_ENSURE_ARG_POINTER(aChild);
+  *aChild = nsnull;
+
+  PRUint32 count = 0;
+  nsresult rv = NS_OK;
+
+  if (mChildren) {
+    rv = mChildren->GetLength(&count);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  if (aChildNum >= static_cast<PRInt32>(count) || count == 0)
+    return NS_ERROR_INVALID_ARG;
+
+  if (aChildNum < 0)
+    aChildNum = count - 1;
+
+  nsCOMPtr<nsIWeakReference> childWeakRef;
+  rv = mChildren->QueryElementAt(aChildNum, NS_GET_IID(nsIWeakReference),
+                                 getter_AddRefs(childWeakRef));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (childWeakRef) {
+    nsCOMPtr<nsIAccessible> childAcc(do_QueryReferent(childWeakRef));
+    NS_IF_ADDREF(*aChild = childAcc);
+  }
+
+  return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessible protected methods
+NS_IMETHODIMP
+nsApplicationAccessible::GetNextSibling(nsIAccessible **aNextSibling)
+{
+  NS_ENSURE_ARG_POINTER(aNextSibling);
+
+  *aNextSibling = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsApplicationAccessible::GetPreviousSibling(nsIAccessible **aPreviousSibling)
+{
+  NS_ENSURE_ARG_POINTER(aPreviousSibling);
+
+  *aPreviousSibling = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsApplicationAccessible::GetIndexInParent(PRInt32 *aIndexInParent)
+{
+  NS_ENSURE_ARG_POINTER(aIndexInParent);
+
+  *aIndexInParent = -1;
+  return NS_OK;
+}
 
 void
 nsApplicationAccessible::CacheChildren()
 {
-  // Nothing to do. Children are keeped up to dated by Add/RemoveRootAccessible
-  // method calls.
-}
-
-nsIAccessible*
-nsApplicationAccessible::GetSiblingAtOffset(PRInt32 aOffset, nsresult* aError)
-{
-  if (IsDefunct()) {
-    if (aError)
-      *aError = NS_ERROR_FAILURE;
-
-    return nsnull;
+  if (!mChildren) {
+    mAccChildCount = eChildCountUninitialized;
+    return;
   }
 
-  if (aError)
-    *aError = NS_OK; // fail peacefully
+  if (mAccChildCount == eChildCountUninitialized) {
+    mAccChildCount = 0;// Prevent reentry
+    nsCOMPtr<nsISimpleEnumerator> enumerator;
+    mChildren->Enumerate(getter_AddRefs(enumerator));
 
-  return nsnull;
+    nsCOMPtr<nsIWeakReference> childWeakRef;
+    nsCOMPtr<nsIAccessible> accessible;
+    nsRefPtr<nsAccessible> prevAcc;
+    PRBool hasMoreElements;
+
+    while(NS_SUCCEEDED(enumerator->HasMoreElements(&hasMoreElements)) &&
+          hasMoreElements) {
+      enumerator->GetNext(getter_AddRefs(childWeakRef));
+      accessible = do_QueryReferent(childWeakRef);
+      if (accessible) {
+        if (prevAcc)
+          prevAcc->SetNextSibling(accessible);
+        else
+          SetFirstChild(accessible);
+
+        prevAcc = nsAccUtils::QueryAccessible(accessible);
+        prevAcc->SetParent(this);
+      }
+    }
+
+    PRUint32 count = 0;
+    mChildren->GetLength(&count);
+    mAccChildCount = static_cast<PRInt32>(count);
+  }
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// Public methods
+// nsApplicationAccessible
 
 nsresult
 nsApplicationAccessible::AddRootAccessible(nsIAccessible *aRootAccessible)
 {
   NS_ENSURE_ARG_POINTER(aRootAccessible);
 
-  if (!mChildren.AppendObject(aRootAccessible))
-    return NS_ERROR_FAILURE;
-
-  nsRefPtr<nsAccessible> rootAcc = nsAccUtils::QueryAccessible(aRootAccessible);
-  rootAcc->SetParent(this);
+  // add by weak reference
+  nsresult rv = mChildren->AppendElement(aRootAccessible, PR_TRUE);
+  NS_ENSURE_SUCCESS(rv, rv);
 
+  InvalidateChildren();
   return NS_OK;
 }
 
@@ -221,8 +280,17 @@ nsApplicationAccessible::RemoveRootAccessible(nsIAccessible *aRootAccessible)
 {
   NS_ENSURE_ARG_POINTER(aRootAccessible);
 
-  // It's not needed to void root accessible parent because this method is
-  // called on root accessible shutdown and its parent will be cleared
-  // properly.
-  return mChildren.RemoveObject(aRootAccessible) ? NS_OK : NS_ERROR_FAILURE;
+  PRUint32 index = 0;
+
+  // we must use weak ref to get the index
+  nsCOMPtr<nsIWeakReference> weakPtr = do_GetWeakReference(aRootAccessible);
+  nsresult rv = mChildren->IndexOf(0, weakPtr, &index);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = mChildren->RemoveElementAt(index);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  InvalidateChildren();
+  return NS_OK;
 }
+
diff --git a/accessible/src/base/nsApplicationAccessible.h b/accessible/src/base/nsApplicationAccessible.h
index 6668df5708bc..e45898e8e558 100644
--- a/accessible/src/base/nsApplicationAccessible.h
+++ b/accessible/src/base/nsApplicationAccessible.h
@@ -63,36 +63,34 @@ public:
 
   // nsISupports
   NS_DECL_ISUPPORTS_INHERITED
-
-  // nsIAccessible
-  NS_IMETHOD GetName(nsAString& aName);
-  NS_IMETHOD GetDescription(nsAString& aValue);
-  NS_IMETHOD GetRole(PRUint32 *aRole);
-  NS_IMETHOD GetState(PRUint32 *aState, PRUint32 *aExtraState);
-
-  NS_IMETHOD GetParent(nsIAccessible **aAccessible);
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(nsApplicationAccessible,
+                                           nsAccessible)
 
   // nsAccessNode
-  virtual PRBool IsDefunct();
   virtual nsresult Init();
 
+  // nsIAccessible
+  NS_IMETHOD GetName(nsAString & aName);
+  NS_IMETHOD GetRole(PRUint32 *aRole);
+  NS_IMETHOD GetParent(nsIAccessible * *aParent);
+  NS_IMETHOD GetNextSibling(nsIAccessible * *aNextSibling);
+  NS_IMETHOD GetPreviousSibling(nsIAccessible **aPreviousSibling);
+  NS_IMETHOD GetIndexInParent(PRInt32 *aIndexInParent);
+  NS_IMETHOD GetChildAt(PRInt32 aChildNum, nsIAccessible **aChild);
+
   // nsAccessible
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
-  virtual nsIAccessible* GetParent();
-
-  virtual void InvalidateChildren();
 
   // nsApplicationAccessible
   virtual nsresult AddRootAccessible(nsIAccessible *aRootAccWrap);
   virtual nsresult RemoveRootAccessible(nsIAccessible *aRootAccWrap);
 
 protected:
-
   // nsAccessible
   virtual void CacheChildren();
-  virtual nsIAccessible* GetSiblingAtOffset(PRInt32 aOffset,
-                                            nsresult *aError = nsnull);
+
+  nsCOMPtr<nsIMutableArray> mChildren;
 };
 
 #endif
diff --git a/accessible/src/base/nsBaseWidgetAccessible.cpp b/accessible/src/base/nsBaseWidgetAccessible.cpp
index eea11a3e0b29..5bd4d105ca3d 100644
--- a/accessible/src/base/nsBaseWidgetAccessible.cpp
+++ b/accessible/src/base/nsBaseWidgetAccessible.cpp
@@ -65,9 +65,7 @@ nsAccessibleWrap(aNode, aShell)
 
 NS_IMPL_ISUPPORTS_INHERITED0(nsLeafAccessible, nsAccessible)
 
-////////////////////////////////////////////////////////////////////////////////
-// nsLeafAccessible: nsAccessible public
-
+// nsAccessible::GetChildAtPoint()
 nsresult
 nsLeafAccessible::GetChildAtPoint(PRInt32 aX, PRInt32 aY,
                                   PRBool aDeepestChild,
@@ -78,13 +76,12 @@ nsLeafAccessible::GetChildAtPoint(PRInt32 aX, PRInt32 aY,
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsLeafAccessible: nsAccessible private
-
+// nsAccessible::CacheChildren()
 void
 nsLeafAccessible::CacheChildren()
 {
   // No children for leaf accessible.
+  mAccChildCount = IsDefunct() ? eChildCountUninitialized : 0;
 }
 
 
diff --git a/accessible/src/base/nsCoreUtils.cpp b/accessible/src/base/nsCoreUtils.cpp
index 0b32085ad579..3d5a88d2e222 100644
--- a/accessible/src/base/nsCoreUtils.cpp
+++ b/accessible/src/base/nsCoreUtils.cpp
@@ -1027,7 +1027,7 @@ nsCoreUtils::GetLastSensibleColumn(nsITreeBoxObject *aTree)
 }
 
 PRUint32
-nsCoreUtils::GetSensibleColumnCount(nsITreeBoxObject *aTree)
+nsCoreUtils::GetSensiblecolumnCount(nsITreeBoxObject *aTree)
 {
   PRUint32 count = 0;
 
diff --git a/accessible/src/base/nsCoreUtils.h b/accessible/src/base/nsCoreUtils.h
index 1eb7a2ee693b..4fa693ad2a9a 100644
--- a/accessible/src/base/nsCoreUtils.h
+++ b/accessible/src/base/nsCoreUtils.h
@@ -413,7 +413,7 @@ public:
   /**
    * Return sensible columns count for the given tree box object.
    */
-  static PRUint32 GetSensibleColumnCount(nsITreeBoxObject *aTree);
+  static PRUint32 GetSensiblecolumnCount(nsITreeBoxObject *aTree);
 
   /**
    * Return sensible column at the given index for the given tree box object.
diff --git a/accessible/src/base/nsDocAccessible.cpp b/accessible/src/base/nsDocAccessible.cpp
index 276a8d745f93..15f30508ad3d 100644
--- a/accessible/src/base/nsDocAccessible.cpp
+++ b/accessible/src/base/nsDocAccessible.cpp
@@ -73,16 +73,16 @@
 #include "nsIXULDocument.h"
 #endif
 
-////////////////////////////////////////////////////////////////////////////////
-// Static member initialization
+//=============================//
+// nsDocAccessible  //
+//=============================//
 
 PRUint32 nsDocAccessible::gLastFocusedAccessiblesState = 0;
 nsIAtom *nsDocAccessible::gLastFocusedFrameType = nsnull;
 
-
-////////////////////////////////////////////////////////////////////////////////
-// Constructor/desctructor
-
+//-----------------------------------------------------
+// construction
+//-----------------------------------------------------
 nsDocAccessible::nsDocAccessible(nsIDOMNode *aDOMNode, nsIWeakReference* aShell):
   nsHyperTextAccessibleWrap(aDOMNode, aShell), mWnd(nsnull),
   mScrollPositionChangedTicks(0), mIsContentLoaded(PR_FALSE),
@@ -129,13 +129,15 @@ nsDocAccessible::nsDocAccessible(nsIDOMNode *aDOMNode, nsIWeakReference* aShell)
   }
 }
 
+//-----------------------------------------------------
+// destruction
+//-----------------------------------------------------
 nsDocAccessible::~nsDocAccessible()
 {
 }
 
-
 ////////////////////////////////////////////////////////////////////////////////
-// nsISupports
+// nsDocAccessible. nsISupports
 
 static PLDHashOperator
 ElementTraverser(const void *aKey, nsIAccessNode *aAccessNode,
@@ -180,10 +182,6 @@ NS_INTERFACE_MAP_END_INHERITING(nsHyperTextAccessible)
 NS_IMPL_ADDREF_INHERITED(nsDocAccessible, nsHyperTextAccessible)
 NS_IMPL_RELEASE_INHERITED(nsDocAccessible, nsHyperTextAccessible)
 
-
-////////////////////////////////////////////////////////////////////////////////
-// nsIAccessible
-
 NS_IMETHODIMP
 nsDocAccessible::GetName(nsAString& aName)
 {
@@ -206,7 +204,6 @@ nsDocAccessible::GetName(nsAString& aName)
   return rv;
 }
 
-// nsAccessible public method
 nsresult
 nsDocAccessible::GetRoleInternal(PRUint32 *aRole)
 {
@@ -245,7 +242,6 @@ nsDocAccessible::GetRoleInternal(PRUint32 *aRole)
   return NS_OK;
 }
 
-// nsAccessible public method
 void
 nsDocAccessible::SetRoleMapEntry(nsRoleMapEntry* aRoleMapEntry)
 {
@@ -286,7 +282,6 @@ nsDocAccessible::GetDescription(nsAString& aDescription)
   return NS_OK;
 }
 
-// nsAccessible public method
 nsresult
 nsDocAccessible::GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState)
 {
@@ -337,7 +332,6 @@ nsDocAccessible::GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState)
   return NS_OK;
 }
 
-// nsAccessible public method
 nsresult
 nsDocAccessible::GetARIAState(PRUint32 *aState, PRUint32 *aExtraState)
 {
@@ -402,9 +396,7 @@ NS_IMETHODIMP nsDocAccessible::TakeFocus()
   return NS_ERROR_FAILURE;
 }
 
-
-////////////////////////////////////////////////////////////////////////////////
-// nsIAccessibleDocument
+// ------- nsIAccessibleDocument Methods (5) ---------------
 
 NS_IMETHODIMP nsDocAccessible::GetURL(nsAString& aURL)
 {
@@ -507,7 +499,6 @@ NS_IMETHODIMP nsDocAccessible::GetDocument(nsIDOMDocument **aDOMDoc)
   return NS_ERROR_FAILURE;
 }
 
-// nsIAccessibleHyperText method
 NS_IMETHODIMP nsDocAccessible::GetAssociatedEditor(nsIEditor **aEditor)
 {
   NS_ENSURE_ARG_POINTER(aEditor);
@@ -566,7 +557,6 @@ NS_IMETHODIMP nsDocAccessible::GetCachedAccessNode(void *aUniqueID, nsIAccessNod
   return NS_OK;
 }
 
-// nsDocAccessible public method
 void
 nsDocAccessible::CacheAccessNode(void *aUniqueID, nsIAccessNode *aAccessNode)
 {
@@ -584,7 +574,6 @@ nsDocAccessible::CacheAccessNode(void *aUniqueID, nsIAccessNode *aAccessNode)
   PutCacheEntry(mAccessNodeCache, aUniqueID, aAccessNode);
 }
 
-// nsDocAccessible public method
 void
 nsDocAccessible::RemoveAccessNodeFromCache(nsIAccessNode *aAccessNode)
 {
@@ -596,8 +585,31 @@ nsDocAccessible::RemoveAccessNodeFromCache(nsIAccessNode *aAccessNode)
   mAccessNodeCache.Remove(uniqueID);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessNode
+NS_IMETHODIMP nsDocAccessible::GetParent(nsIAccessible **aParent)
+{
+  // Hook up our new accessible with our parent
+  *aParent = nsnull;
+  NS_ENSURE_TRUE(mDocument, NS_ERROR_FAILURE);
+  if (!mParent) {
+    nsIDocument *parentDoc = mDocument->GetParentDocument();
+    NS_ENSURE_TRUE(parentDoc, NS_ERROR_FAILURE);
+    nsIContent *ownerContent = parentDoc->FindContentForSubDocument(mDocument);
+    nsCOMPtr<nsIDOMNode> ownerNode(do_QueryInterface(ownerContent));
+    if (ownerNode) {
+      nsCOMPtr<nsIAccessibilityService> accService =
+        do_GetService("@mozilla.org/accessibilityService;1");
+      if (accService) {
+        // XXX aaronl: ideally we would traverse the presshell chain
+        // Since there's no easy way to do that, we cheat and use
+        // the document hierarchy. GetAccessibleFor() is bad because
+        // it doesn't support our concept of multiple presshells per doc.
+        // It should be changed to use GetAccessibleInWeakShell()
+        accService->GetAccessibleFor(ownerNode, getter_AddRefs(mParent));
+      }
+    }
+  }
+  return mParent ? nsAccessible::GetParent(aParent) : NS_ERROR_FAILURE;
+}
 
 nsresult
 nsDocAccessible::Init()
@@ -606,7 +618,8 @@ nsDocAccessible::Init()
 
   AddEventListeners();
 
-  GetParent(); // Ensure outer doc mParent accessible.
+  nsCOMPtr<nsIAccessible> parentAccessible;  // Ensure outer doc mParent accessible
+  GetParent(getter_AddRefs(parentAccessible));
 
   nsresult rv = nsHyperTextAccessibleWrap::Init();
   NS_ENSURE_SUCCESS(rv, rv);
@@ -667,7 +680,6 @@ nsDocAccessible::Shutdown()
   return NS_OK;
 }
 
-// nsDocAccessible protected member
 void nsDocAccessible::ShutdownChildDocuments(nsIDocShellTreeItem *aStart)
 {
   nsCOMPtr<nsIDocShellTreeNode> treeNode(do_QueryInterface(aStart));
@@ -713,7 +725,6 @@ nsDocAccessible::IsDefunct()
   return !mDocument;
 }
 
-// nsDocAccessible protected member
 void nsDocAccessible::GetBoundsRect(nsRect& aBounds, nsIFrame** aRelativeFrame)
 {
   *aRelativeFrame = GetFrame();
@@ -757,7 +768,7 @@ void nsDocAccessible::GetBoundsRect(nsRect& aBounds, nsIFrame** aRelativeFrame)
   }
 }
 
-// nsDocAccessible protected member
+
 nsresult nsDocAccessible::AddEventListeners()
 {
   // 1) Set up scroll position listener
@@ -803,7 +814,6 @@ nsresult nsDocAccessible::AddEventListeners()
   return NS_OK;
 }
 
-// nsDocAccessible protected member
 nsresult nsDocAccessible::RemoveEventListeners()
 {
   // Remove listeners associated with content documents
@@ -850,7 +860,6 @@ nsresult nsDocAccessible::RemoveEventListeners()
   return NS_OK;
 }
 
-// nsDocAccessible public member
 void
 nsDocAccessible::FireDocLoadEvents(PRUint32 aEventType)
 {
@@ -880,7 +889,8 @@ nsDocAccessible::FireDocLoadEvents(PRUint32 aEventType)
   if (isFinished) {
     // Need to wait until scrollable view is available
     AddScrollListener();
-    nsRefPtr<nsAccessible> acc(nsAccUtils::QueryAccessible(GetParent()));
+    nsCOMPtr<nsIAccessible> parent(nsAccessible::GetParent());
+    nsRefPtr<nsAccessible> acc(nsAccUtils::QueryAccessible(parent));
     if (acc) {
       // Make the parent forget about the old document as a child
       acc->InvalidateChildren();
@@ -944,7 +954,6 @@ void nsDocAccessible::ScrollTimerCallback(nsITimer *aTimer, void *aClosure)
   }
 }
 
-// nsDocAccessible protected member
 void nsDocAccessible::AddScrollListener()
 {
   nsCOMPtr<nsIPresShell> presShell(do_QueryReferent(mWeakShell));
@@ -961,7 +970,6 @@ void nsDocAccessible::AddScrollListener()
     scrollableView->AddScrollPositionListener(this);
 }
 
-// nsDocAccessible protected member
 void nsDocAccessible::RemoveScrollListener()
 {
   nsCOMPtr<nsIPresShell> presShell(do_QueryReferent(mWeakShell));
@@ -978,9 +986,6 @@ void nsDocAccessible::RemoveScrollListener()
     scrollableView->RemoveScrollPositionListener(this);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsIScrollPositionListener
-
 NS_IMETHODIMP nsDocAccessible::ScrollPositionWillChange(nsIScrollableView *aView, nscoord aX, nscoord aY)
 {
   return NS_OK;
@@ -1007,9 +1012,6 @@ NS_IMETHODIMP nsDocAccessible::ScrollPositionDidChange(nsIScrollableView *aScrol
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsIObserver
-
 NS_IMETHODIMP nsDocAccessible::Observe(nsISupports *aSubject, const char *aTopic,
                                        const PRUnichar *aData)
 {
@@ -1024,7 +1026,7 @@ NS_IMETHODIMP nsDocAccessible::Observe(nsISupports *aSubject, const char *aTopic
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
+  ///////////////////////////////////////////////////////////////////////
 // nsIDocumentObserver
 
 NS_IMPL_NSIDOCUMENTOBSERVER_CORE_STUB(nsDocAccessible)
@@ -1060,7 +1062,7 @@ nsDocAccessible::AttributeChanged(nsIDocument *aDocument, nsIContent* aContent,
   }
 }
 
-// nsDocAccessible protected member
+
 void
 nsDocAccessible::AttributeChangedImpl(nsIContent* aContent, PRInt32 aNameSpaceID, nsIAtom* aAttribute)
 {
@@ -1211,7 +1213,6 @@ nsDocAccessible::AttributeChangedImpl(nsIContent* aContent, PRInt32 aNameSpaceID
   }
 }
 
-// nsDocAccessible protected member
 void
 nsDocAccessible::ARIAAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute)
 {
@@ -1361,7 +1362,6 @@ void nsDocAccessible::ContentAppended(nsIDocument *aDocument,
   }
 }
 
-
 void nsDocAccessible::ContentStatesChanged(nsIDocument* aDocument,
                                            nsIContent* aContent1,
                                            nsIContent* aContent2,
@@ -1417,45 +1417,6 @@ nsDocAccessible::ParentChainChanged(nsIContent *aContent)
 {
 }
 
-
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessible
-
-nsIAccessible*
-nsDocAccessible::GetParent()
-{
-  if (IsDefunct())
-    return nsnull;
-
-  if (mParent)
-    return mParent;
-
-  nsIDocument* parentDoc = mDocument->GetParentDocument();
-  if (!parentDoc)
-    return nsnull;
-
-  nsIContent* ownerContent = parentDoc->FindContentForSubDocument(mDocument);
-  nsCOMPtr<nsIDOMNode> ownerNode(do_QueryInterface(ownerContent));
-  if (ownerNode) {
-    nsCOMPtr<nsIAccessibilityService> accService = GetAccService();
-    if (accService) {
-      // XXX aaronl: ideally we would traverse the presshell chain. Since
-      // there's no easy way to do that, we cheat and use the document
-      // hierarchy. GetAccessibleFor() is bad because it doesn't support our
-      // concept of multiple presshells per doc.
-      // It should be changed to use GetAccessibleInWeakShell()
-      accService->GetAccessibleFor(ownerNode, getter_AddRefs(mParent));
-    }
-  }
-
-  NS_ASSERTION(mParent, "No parent for not root document accessible!");
-  return mParent;
-}
-
-
-////////////////////////////////////////////////////////////////////////////////
-// Protected members
-
 void
 nsDocAccessible::FireValueChangeForTextFields(nsIAccessible *aPossibleTextFieldAccessible)
 {
@@ -1610,8 +1571,7 @@ nsDocAccessible::CreateTextChangeEventForNode(nsIAccessible *aContainerAccessibl
 
   return event;
 }
-
-// nsDocAccessible public member
+  
 nsresult
 nsDocAccessible::FireDelayedAccessibleEvent(PRUint32 aEventType,
                                             nsIDOMNode *aDOMNode,
@@ -1625,7 +1585,6 @@ nsDocAccessible::FireDelayedAccessibleEvent(PRUint32 aEventType,
   return FireDelayedAccessibleEvent(event);
 }
 
-// nsDocAccessible public member
 nsresult
 nsDocAccessible::FireDelayedAccessibleEvent(nsIAccessibleEvent *aEvent)
 {
@@ -1994,7 +1953,6 @@ void nsDocAccessible::RefreshNodes(nsIDOMNode *aStartNode)
   mAccessNodeCache.Remove(uniqueID);
 }
 
-// nsDocAccessible public member
 void
 nsDocAccessible::InvalidateCacheSubtree(nsIContent *aChild,
                                         PRUint32 aChangeType)
@@ -2222,7 +2180,6 @@ nsDocAccessible::InvalidateCacheSubtree(nsIContent *aChild,
   FireDelayedAccessibleEvent(reorderEvent);
 }
 
-// nsIAccessibleDocument method
 NS_IMETHODIMP
 nsDocAccessible::GetAccessibleInParentChain(nsIDOMNode *aNode,
                                             PRBool aCanCreate,
diff --git a/accessible/src/base/nsDocAccessible.h b/accessible/src/base/nsDocAccessible.h
index d351be665a16..7926dccd90f7 100644
--- a/accessible/src/base/nsDocAccessible.h
+++ b/accessible/src/base/nsDocAccessible.h
@@ -87,6 +87,7 @@ public:
   NS_IMETHOD GetDescription(nsAString& aDescription);
   NS_IMETHOD GetAttributes(nsIPersistentProperties **aAttributes);
   NS_IMETHOD GetFocusedChild(nsIAccessible **aFocusedChild);
+  NS_IMETHOD GetParent(nsIAccessible **aParent);
   NS_IMETHOD TakeFocus(void);
 
   // nsIScrollPositionListener
@@ -110,9 +111,7 @@ public:
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
   virtual nsresult GetARIAState(PRUint32 *aState, PRUint32 *aExtraState);
-
   virtual void SetRoleMapEntry(nsRoleMapEntry* aRoleMapEntry);
-  virtual nsIAccessible* GetParent();
 
   // nsIAccessibleText
   NS_IMETHOD GetAssociatedEditor(nsIEditor **aEditor);
diff --git a/accessible/src/base/nsOuterDocAccessible.cpp b/accessible/src/base/nsOuterDocAccessible.cpp
index df962beffa7b..b42b062c03f0 100644
--- a/accessible/src/base/nsOuterDocAccessible.cpp
+++ b/accessible/src/base/nsOuterDocAccessible.cpp
@@ -99,11 +99,25 @@ nsOuterDocAccessible::GetChildAtPoint(PRInt32 aX, PRInt32 aY,
   return NS_OK;
 }
 
-void
-nsOuterDocAccessible::CacheChildren()
-{
-  // An outer doc accessible usually has 1 nsDocAccessible child, but could have
-  // none if we can't get to the inner documnet.
+void nsOuterDocAccessible::CacheChildren()
+{  
+  // An outer doc accessible usually has 1 nsDocAccessible child,
+  // but could have none if we can't get to the inner documnet
+  if (!mWeakShell) {
+    mAccChildCount = eChildCountUninitialized;
+    return;   // This outer doc node has been shut down
+  }
+  if (mAccChildCount != eChildCountUninitialized) {
+    return;
+  }
+
+  InvalidateChildren();
+  mAccChildCount = 0;
+
+  // In these variable names, "outer" relates to the nsOuterDocAccessible
+  // as opposed to the nsDocAccessibleWrap which is "inner".
+  // The outer node is a something like a <browser>, <frame>, <iframe>, <page> or
+  // <editor> tag, whereas the inner node corresponds to the inner document root.
 
   nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));
   NS_ASSERTION(content, "No nsIContent for <browser>/<iframe>/<editor> dom node");
@@ -120,15 +134,18 @@ nsOuterDocAccessible::CacheChildren()
   }
 
   nsCOMPtr<nsIAccessible> innerAccessible;
-  nsCOMPtr<nsIAccessibilityService> accService = GetAccService();
+  nsCOMPtr<nsIAccessibilityService> accService = 
+    do_GetService("@mozilla.org/accessibilityService;1");
   accService->GetAccessibleFor(innerNode, getter_AddRefs(innerAccessible));
   nsRefPtr<nsAccessible> innerAcc(nsAccUtils::QueryAccessible(innerAccessible));
   if (!innerAcc)
     return;
 
   // Success getting inner document as first child -- now we cache it.
-  mChildren.AppendObject(innerAccessible);
+  mAccChildCount = 1;
+  SetFirstChild(innerAccessible); // weak ref
   innerAcc->SetParent(this);
+  innerAcc->SetNextSibling(nsnull);
 }
 
 nsresult
diff --git a/accessible/src/base/nsOuterDocAccessible.h b/accessible/src/base/nsOuterDocAccessible.h
index 3141d8e5862a..bb0a3accd56f 100644
--- a/accessible/src/base/nsOuterDocAccessible.h
+++ b/accessible/src/base/nsOuterDocAccessible.h
@@ -42,14 +42,8 @@
 #include "nsAccessibleWrap.h"
 #include "nsIAccessible.h"
 
-/**
- * Used for <browser>, <frame>, <iframe>, <page> or editor> elements.
- * 
- * In these variable names, "outer" relates to the nsOuterDocAccessible as
- * opposed to the nsDocAccessibleWrap which is "inner". The outer node is
- * a something like tags listed above, whereas the inner node corresponds to
- * the inner document root.
- */
+class nsIWeakReference;
+
 class nsOuterDocAccessible : public nsAccessibleWrap
 {
   // XXX: why is it private?
@@ -76,7 +70,7 @@ public:
 
 protected:
   // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 };
 
 #endif  
diff --git a/accessible/src/base/nsRootAccessible.cpp b/accessible/src/base/nsRootAccessible.cpp
index 04d333ad5739..ff26cbeadd5d 100644
--- a/accessible/src/base/nsRootAccessible.cpp
+++ b/accessible/src/base/nsRootAccessible.cpp
@@ -84,9 +84,6 @@
 #include "nsIXULWindow.h"
 #endif
 
-////////////////////////////////////////////////////////////////////////////////
-// nsISupports
-
 // Expanded version of NS_IMPL_ISUPPORTS_INHERITED2 
 // so we can QI directly to concrete nsRootAccessible
 NS_IMPL_QUERY_HEAD(nsRootAccessible)
@@ -99,21 +96,21 @@ NS_IMPL_QUERY_TAIL_INHERITING(nsDocAccessible)
 NS_IMPL_ADDREF_INHERITED(nsRootAccessible, nsDocAccessible) 
 NS_IMPL_RELEASE_INHERITED(nsRootAccessible, nsDocAccessible)
 
-////////////////////////////////////////////////////////////////////////////////
-// Constructor/desctructor
-
+//-----------------------------------------------------
+// construction 
+//-----------------------------------------------------
 nsRootAccessible::nsRootAccessible(nsIDOMNode *aDOMNode, nsIWeakReference* aShell):
   nsDocAccessibleWrap(aDOMNode, aShell)
 {
 }
 
+//-----------------------------------------------------
+// destruction
+//-----------------------------------------------------
 nsRootAccessible::~nsRootAccessible()
 {
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsIAccessible
-
 /* readonly attribute AString name; */
 NS_IMETHODIMP
 nsRootAccessible::GetName(nsAString& aName)
@@ -135,6 +132,21 @@ nsRootAccessible::GetName(nsAString& aName)
   return document->GetTitle(aName);
 }
 
+/* readonly attribute nsIAccessible accParent; */
+NS_IMETHODIMP nsRootAccessible::GetParent(nsIAccessible * *aParent) 
+{
+  NS_ENSURE_ARG_POINTER(aParent);
+  *aParent = nsnull;
+
+  if (!mParent) {
+    nsRefPtr<nsApplicationAccessibleWrap> root = GetApplicationAccessible();
+    mParent = root;
+  }
+
+  NS_IF_ADDREF(*aParent = mParent);
+  return NS_OK;
+}
+
 /* readonly attribute unsigned long accRole; */
 nsresult
 nsRootAccessible::GetRoleInternal(PRUint32 *aRole) 
@@ -160,7 +172,6 @@ nsRootAccessible::GetRoleInternal(PRUint32 *aRole)
   return nsDocAccessibleWrap::GetRoleInternal(aRole);
 }
 
-// nsRootAccessible protected member
 #ifdef MOZ_XUL
 PRUint32 nsRootAccessible::GetChromeFlags()
 {
@@ -570,8 +581,7 @@ void nsRootAccessible::FireCurrentFocusEvent()
   }
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsIDOMEventListener
+// --------------- nsIDOMEventListener Methods (3) ------------------------
 
 NS_IMETHODIMP nsRootAccessible::HandleEvent(nsIDOMEvent* aEvent)
 {
@@ -585,8 +595,6 @@ NS_IMETHODIMP nsRootAccessible::HandleEvent(nsIDOMEvent* aEvent)
   return HandleEventWithTarget(aEvent, targetNode);
 }
 
-
-// nsRootAccessible protected member
 nsresult nsRootAccessible::HandleEventWithTarget(nsIDOMEvent* aEvent,
                                                  nsIDOMNode* aTargetNode)
 {
@@ -938,9 +946,6 @@ void nsRootAccessible::FireFocusCallback(nsITimer *aTimer, void *aClosure)
   rootAccessible->FireCurrentFocusEvent();
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessNode
-
 nsresult
 nsRootAccessible::Init()
 {
@@ -975,7 +980,6 @@ nsRootAccessible::Shutdown()
   return nsDocAccessibleWrap::Shutdown();
 }
 
-// nsRootAccessible protected member
 already_AddRefed<nsIDocShellTreeItem>
 nsRootAccessible::GetContentDocShell(nsIDocShellTreeItem *aStart)
 {
@@ -1032,7 +1036,6 @@ nsRootAccessible::GetContentDocShell(nsIDocShellTreeItem *aStart)
   return nsnull;
 }
 
-// nsIAccessible method
 NS_IMETHODIMP
 nsRootAccessible::GetRelationByType(PRUint32 aRelationType,
                                     nsIAccessibleRelation **aRelation)
@@ -1059,20 +1062,6 @@ nsRootAccessible::GetRelationByType(PRUint32 aRelationType,
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsAccessible
-
-nsIAccessible*
-nsRootAccessible::GetParent()
-{
-  // Parent has been setted in nsApplicationAccesible::AddRootAccessible()
-  // when root accessible was intialized.
-  return mParent;
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// nsDocAccessible
-
 void
 nsRootAccessible::FireDocLoadEvents(PRUint32 aEventType)
 {
@@ -1095,9 +1084,6 @@ nsRootAccessible::FireDocLoadEvents(PRUint32 aEventType)
                       aEventType == nsIAccessibleEvent::EVENT_DOCUMENT_LOAD_STOPPED);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// Protected members
-
 nsresult
 nsRootAccessible::HandlePopupShownEvent(nsIAccessible *aAccessible)
 {
diff --git a/accessible/src/base/nsRootAccessible.h b/accessible/src/base/nsRootAccessible.h
index 8e39079a1c53..74dc2df75f8b 100644
--- a/accessible/src/base/nsRootAccessible.h
+++ b/accessible/src/base/nsRootAccessible.h
@@ -74,6 +74,7 @@ public:
 
   // nsIAccessible
   NS_IMETHOD GetName(nsAString& aName);
+  NS_IMETHOD GetParent(nsIAccessible * *aParent);
   NS_IMETHOD GetRelationByType(PRUint32 aRelationType,
                                nsIAccessibleRelation **aRelation);
 
@@ -87,7 +88,6 @@ public:
   // nsAccessible
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
-  virtual nsIAccessible* GetParent();
 
   // nsDocAccessible
   virtual void FireDocLoadEvents(PRUint32 aEventType);
diff --git a/accessible/src/base/nsTextAccessible.cpp b/accessible/src/base/nsTextAccessible.cpp
index cbafb2cb372a..8ea0347bf140 100644
--- a/accessible/src/base/nsTextAccessible.cpp
+++ b/accessible/src/base/nsTextAccessible.cpp
@@ -70,4 +70,5 @@ void
 nsTextAccessible::CacheChildren()
 {
   // No children for text accessible.
+  mAccChildCount = IsDefunct() ? eChildCountUninitialized : 0;
 }
diff --git a/accessible/src/html/nsHTMLAreaAccessible.cpp b/accessible/src/html/nsHTMLAreaAccessible.cpp
index 6d0de66c46ef..c2507d4cfffd 100644
--- a/accessible/src/html/nsHTMLAreaAccessible.cpp
+++ b/accessible/src/html/nsHTMLAreaAccessible.cpp
@@ -155,4 +155,5 @@ void
 nsHTMLAreaAccessible::CacheChildren()
 {
   // No children for aria accessible.
+  mAccChildCount = IsDefunct() ? eChildCountUninitialized : 0;
 }
diff --git a/accessible/src/html/nsHTMLImageAccessible.cpp b/accessible/src/html/nsHTMLImageAccessible.cpp
index 29d235fc9564..a90c0a410ce8 100644
--- a/accessible/src/html/nsHTMLImageAccessible.cpp
+++ b/accessible/src/html/nsHTMLImageAccessible.cpp
@@ -155,28 +155,42 @@ nsHTMLImageAccessible::GetRoleInternal(PRUint32 *aRole)
   return NS_OK;
 }
 
-void 
-nsHTMLImageAccessible::CacheChildren()
+void nsHTMLImageAccessible::CacheChildren()
 {
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+
+  if (mAccChildCount != eChildCountUninitialized) {
+    return;
+  }
+
+  mAccChildCount = 0;
   nsCOMPtr<nsIDOMHTMLCollection> mapAreas = GetAreaCollection();
   if (!mapAreas)
     return;
 
-  PRUint32 areaCount = 0;
-  mapAreas->GetLength(&areaCount);
-
+  PRUint32 numMapAreas;
+  mapAreas->GetLength(&numMapAreas);
+  PRInt32 childCount = 0;
+  
   nsCOMPtr<nsIAccessible> areaAccessible;
-  nsRefPtr<nsAccessible> areaAcc;
+  nsRefPtr<nsAccessible> prevAcc;
+  while (childCount < (PRInt32)numMapAreas && 
+         (areaAccessible = GetAreaAccessible(mapAreas, childCount)) != nsnull) {
+    if (prevAcc)
+      prevAcc->SetNextSibling(areaAccessible);
+    else
+      SetFirstChild(areaAccessible);
 
-  for (PRUint32 areaIdx = 0; areaIdx < areaCount; areaIdx++) {
-    areaAccessible = GetAreaAccessible(mapAreas, areaIdx);
-    if (!areaAccessible)
-      return;
+    ++ childCount;
 
-    mChildren.AppendObject(areaAccessible);
-    areaAcc = nsAccUtils::QueryObject<nsAccessible>(areaAccessible);
-    areaAcc->SetParent(this);
+    prevAcc = nsAccUtils::QueryAccessible(areaAccessible);
+    prevAcc->SetParent(this);
   }
+  mAccChildCount = childCount;
 }
 
 NS_IMETHODIMP
diff --git a/accessible/src/html/nsHTMLImageAccessible.h b/accessible/src/html/nsHTMLImageAccessible.h
index e735e91ecd4e..55a4f057807b 100644
--- a/accessible/src/html/nsHTMLImageAccessible.h
+++ b/accessible/src/html/nsHTMLImageAccessible.h
@@ -83,7 +83,6 @@ protected:
   // nsAccessible
   virtual void CacheChildren();
 
-  // nsHTMLImageAccessible
   already_AddRefed<nsIDOMHTMLCollection> GetAreaCollection();
   already_AddRefed<nsIAccessible>
     GetAreaAccessible(nsIDOMHTMLCollection* aAreaNodes, PRInt32 aAreaNum);
diff --git a/accessible/src/html/nsHTMLSelectAccessible.cpp b/accessible/src/html/nsHTMLSelectAccessible.cpp
index 5a4dbd4497b5..3d3ffcf3f109 100644
--- a/accessible/src/html/nsHTMLSelectAccessible.cpp
+++ b/accessible/src/html/nsHTMLSelectAccessible.cpp
@@ -305,9 +305,7 @@ NS_IMETHODIMP nsHTMLSelectableAccessible::SelectAllSelection(PRBool *_retval)
 /**  First, the common widgets                             */
 /** ------------------------------------------------------ */
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectListAccessible
-////////////////////////////////////////////////////////////////////////////////
+/** ----- nsHTMLSelectListAccessible ----- */
 
 /** Default Constructor */
 nsHTMLSelectListAccessible::nsHTMLSelectListAccessible(nsIDOMNode* aDOMNode, 
@@ -316,9 +314,11 @@ nsHTMLSelectListAccessible::nsHTMLSelectListAccessible(nsIDOMNode* aDOMNode,
 {
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectListAccessible: nsAccessible public
-
+/**
+  * As a nsHTMLSelectListAccessible we can have the following states:
+  *     nsIAccessibleStates::STATE_MULTISELECTABLE
+  *     nsIAccessibleStates::STATE_EXTSELECTABLE
+  */
 nsresult
 nsHTMLSelectListAccessible::GetStateInternal(PRUint32 *aState,
                                              PRUint32 *aExtraState)
@@ -327,10 +327,6 @@ nsHTMLSelectListAccessible::GetStateInternal(PRUint32 *aState,
                                                              aExtraState);
   NS_ENSURE_A11Y_SUCCESS(rv, rv);
 
-  // As a nsHTMLSelectListAccessible we can have the following states:
-  //   nsIAccessibleStates::STATE_MULTISELECTABLE
-  //   nsIAccessibleStates::STATE_EXTSELECTABLE
-
   nsCOMPtr<nsIDOMHTMLSelectElement> select (do_QueryInterface(mDOMNode));
   if (select) {
     if (*aState & nsIAccessibleStates::STATE_FOCUSED) {
@@ -364,63 +360,109 @@ nsHTMLSelectListAccessible::GetRoleInternal(PRUint32 *aRole)
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectListAccessible: nsAccessible protected
-
-void
-nsHTMLSelectListAccessible::CacheChildren()
+already_AddRefed<nsIAccessible>
+nsHTMLSelectListAccessible::AccessibleForOption(nsIAccessibilityService *aAccService,
+                                                nsIContent *aContent,
+                                                nsIAccessible *aLastGoodAccessible,
+                                                PRInt32 *aChildCount)
 {
-  // Cache accessibles for <optgroup> and <option> DOM decendents as children,
-  // as well as the accessibles for them. Avoid whitespace text nodes. We want
-  // to count all the <optgroup>s and <option>s as children because we want
-  // a flat tree under the Select List.
-  
-  nsCOMPtr<nsIContent> selectContent(do_QueryInterface(mDOMNode));
-  CacheOptSiblings(selectContent);
+  nsCOMPtr<nsIDOMNode> domNode(do_QueryInterface(aContent));
+  NS_ASSERTION(domNode, "DOM node is null");
+  // Accessibility service will initialize & cache any accessibles created
+  nsCOMPtr<nsIAccessible> accessible;
+  aAccService->GetAccessibleInWeakShell(domNode, mWeakShell, getter_AddRefs(accessible));
+  nsRefPtr<nsAccessible> acc(nsAccUtils::QueryAccessible(accessible));
+  if (!acc)
+    return nsnull;
+
+  ++ *aChildCount;
+  acc->SetParent(this);
+  nsRefPtr<nsAccessible> prevAcc =
+    nsAccUtils::QueryAccessible(aLastGoodAccessible);
+  if (prevAcc)
+    prevAcc->SetNextSibling(accessible);
+
+  if (!mFirstChild)
+    mFirstChild = accessible;
+
+  return accessible.forget();
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectListAccessible protected
-
-void
-nsHTMLSelectListAccessible::CacheOptSiblings(nsIContent *aParentContent)
+already_AddRefed<nsIAccessible>
+nsHTMLSelectListAccessible::CacheOptSiblings(nsIAccessibilityService *aAccService,
+                                             nsIContent *aParentContent,
+                                             nsIAccessible *aLastGoodAccessible,
+                                             PRInt32 *aChildCount)
 {
+  // Recursive helper for CacheChildren()
+
   PRUint32 numChildren = aParentContent->GetChildCount();
+  nsCOMPtr<nsIAccessible> lastGoodAccessible(aLastGoodAccessible);
+  nsCOMPtr<nsIAccessible> newAccessible;
+
   for (PRUint32 count = 0; count < numChildren; count ++) {
     nsIContent *childContent = aParentContent->GetChildAt(count);
     if (!childContent->IsHTML()) {
       continue;
     }
-
     nsCOMPtr<nsIAtom> tag = childContent->Tag();
-    if (tag == nsAccessibilityAtoms::option ||
-        tag == nsAccessibilityAtoms::optgroup) {
-
-      // Get an accessible for option or optgroup and cache it.
-      nsCOMPtr<nsIDOMNode> childNode(do_QueryInterface(childContent));
-
-      nsCOMPtr<nsIAccessible> accessible;
-      GetAccService()->GetAccessibleInWeakShell(childNode, mWeakShell,
-                                                getter_AddRefs(accessible));
-      if (accessible) {
-        mChildren.AppendObject(accessible);
-
-        nsRefPtr<nsAccessible> acc =
-          nsAccUtils::QueryObject<nsAccessible>(accessible);
-        acc->SetParent(this);
+    if (tag == nsAccessibilityAtoms::option || tag == nsAccessibilityAtoms::optgroup) {
+      newAccessible = AccessibleForOption(aAccService,
+                                           childContent,
+                                           lastGoodAccessible,
+                                           aChildCount);
+      if (newAccessible) {
+        lastGoodAccessible = newAccessible;
+      }
+      if (tag == nsAccessibilityAtoms::optgroup) {
+        newAccessible = CacheOptSiblings(aAccService, childContent,
+                                         lastGoodAccessible, aChildCount);
+        if (newAccessible) {
+          lastGoodAccessible = newAccessible;
+        }
       }
-
-      // Deep down into optgroup element.
-      if (tag == nsAccessibilityAtoms::optgroup)
-        CacheOptSiblings(childContent);
     }
   }
+
+  if (lastGoodAccessible) {
+    nsRefPtr<nsAccessible> lastAcc =
+      nsAccUtils::QueryAccessible(lastGoodAccessible);
+    lastAcc->SetNextSibling(nsnull);
+  }
+
+  return lastGoodAccessible.forget();
 }
 
+/**
+  * Cache the children and child count of a Select List Accessible. We want to count 
+  *  all the <optgroup>s and <option>s as children because we want a 
+  *  flat tree under the Select List.
+  */
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectOptionAccessible
-////////////////////////////////////////////////////////////////////////////////
+void nsHTMLSelectListAccessible::CacheChildren()
+{
+  // Cache the number of <optgroup> and <option> DOM decendents,
+  // as well as the accessibles for them. Avoid whitespace text nodes.
+
+  nsCOMPtr<nsIContent> selectContent(do_QueryInterface(mDOMNode));
+  nsCOMPtr<nsIAccessibilityService> accService(do_GetService("@mozilla.org/accessibilityService;1"));
+  if (!selectContent || !accService) {
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+
+  if (mAccChildCount != eChildCountUninitialized) {
+    return;
+  }
+
+  mAccChildCount = 0; // Avoid reentry
+  PRInt32 childCount = 0;
+  nsCOMPtr<nsIAccessible> lastGoodAccessible =
+    CacheOptSiblings(accService, selectContent, nsnull, &childCount);
+  mAccChildCount = childCount;
+}
+
+/** ----- nsHTMLSelectOptionAccessible ----- */
 
 /** Default Constructor */
 nsHTMLSelectOptionAccessible::nsHTMLSelectOptionAccessible(nsIDOMNode* aDOMNode, nsIWeakReference* aShell):
@@ -843,9 +885,7 @@ nsIContent* nsHTMLSelectOptionAccessible::GetSelectState(PRUint32* aState,
   return nsnull; 
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectOptGroupAccessible
-////////////////////////////////////////////////////////////////////////////////
+/** ----- nsHTMLSelectOptGroupAccessible ----- */
 
 /** Default Constructor */
 nsHTMLSelectOptGroupAccessible::nsHTMLSelectOptGroupAccessible(nsIDOMNode* aDOMNode, nsIWeakReference* aShell):
@@ -889,26 +929,29 @@ NS_IMETHODIMP nsHTMLSelectOptGroupAccessible::GetNumActions(PRUint8 *_retval)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLSelectOptGroupAccessible: nsAccessible protected
-
-void
-nsHTMLSelectOptGroupAccessible::CacheChildren()
+void nsHTMLSelectOptGroupAccessible::CacheChildren()
 {
-  // XXX To do (bug 378612) - create text child for the anonymous attribute
-  // content, so that nsIAccessibleText is supported for the <optgroup> as it is
-  // for an <option>. Attribute content is what layout creates for
-  // the label="foo" on the <optgroup>. See eStyleContentType_Attr and
-  // CreateAttributeContent() in nsCSSFrameConstructor
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+
+  if (mAccChildCount == eChildCountUninitialized) {
+    // XXX To do (bug 378612) - create text child for the anonymous attribute content, so that
+    // nsIAccessibleText is supported for the <optgroup> as it is for an <option>
+    // Attribute content is what layout creates for the label="foo" on the <optgroup>
+    // See eStyleContentType_Attr and CreateAttributeContent() in nsCSSFrameConstructor
+    mAccChildCount = 0;
+    SetFirstChild(nsnull);
+  }
 }
 
 /** ------------------------------------------------------ */
 /**  Finally, the Combobox widgets                         */
 /** ------------------------------------------------------ */
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLComboboxAccessible
-////////////////////////////////////////////////////////////////////////////////
+/** ----- nsHTMLComboboxAccessible ----- */
 
 nsHTMLComboboxAccessible::nsHTMLComboboxAccessible(nsIDOMNode* aDOMNode, nsIWeakReference* aShell):
 nsAccessibleWrap(aDOMNode, aShell)
@@ -923,32 +966,46 @@ nsHTMLComboboxAccessible::GetRoleInternal(PRUint32 *aRole)
   return NS_OK;
 }
 
-void
-nsHTMLComboboxAccessible::CacheChildren()
+void nsHTMLComboboxAccessible::CacheChildren()
 {
-  nsIFrame* frame = GetFrame();
-  if (!frame)
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
     return;
-
-  nsIComboboxControlFrame *comboFrame = do_QueryFrame(frame);
-  if (!comboFrame)
-    return;
-
-  nsIFrame *listFrame = comboFrame->GetDropDown();
-  if (!listFrame)
-    return;
-
-  if (!mListAccessible) {
-    mListAccessible = 
-      new nsHTMLComboboxListAccessible(mParent, mDOMNode, mWeakShell);
-    if (!mListAccessible)
-      return;
-
-    mListAccessible->Init();
   }
 
-  mChildren.AppendObject(mListAccessible);
-  mListAccessible->SetParent(this);
+  if (mAccChildCount == eChildCountUninitialized) {
+    mAccChildCount = 0;
+
+    nsIFrame *frame = GetFrame();
+    if (!frame) {
+      return;
+    }
+    nsIComboboxControlFrame *comboFrame = do_QueryFrame(frame);
+    if (!comboFrame) {
+      return;
+    }
+    nsIFrame *listFrame = comboFrame->GetDropDown();
+    if (!listFrame) {
+      return;
+    }
+
+    if (!mListAccessible) {
+      mListAccessible = 
+        new nsHTMLComboboxListAccessible(mParent, mDOMNode, mWeakShell);
+      if (!mListAccessible)
+        return;
+
+      mListAccessible->Init();
+    }
+
+    SetFirstChild(mListAccessible);
+
+    mListAccessible->SetParent(this);
+    mListAccessible->SetNextSibling(nsnull);
+
+    ++ mAccChildCount;  // List accessible child successfully added
+  }
 }
 
 nsresult
@@ -1097,7 +1154,6 @@ NS_IMETHODIMP nsHTMLComboboxAccessible::GetActionName(PRUint8 aIndex, nsAString&
   return NS_OK;
 }
 
-
 ////////////////////////////////////////////////////////////////////////////////
 // nsHTMLComboboxListAccessible
 ////////////////////////////////////////////////////////////////////////////////
@@ -1149,6 +1205,13 @@ nsHTMLComboboxListAccessible::GetStateInternal(PRUint32 *aState,
   return NS_OK;
 }
 
+/** Return our cached parent */
+NS_IMETHODIMP nsHTMLComboboxListAccessible::GetParent(nsIAccessible **aParent)
+{
+  NS_IF_ADDREF(*aParent = mParent);
+  return NS_OK;
+}
+
 NS_IMETHODIMP nsHTMLComboboxListAccessible::GetUniqueID(void **aUniqueID)
 {
   // Since mDOMNode is same for all tree item, use |this| pointer as the unique Id
@@ -1164,10 +1227,11 @@ void nsHTMLComboboxListAccessible::GetBoundsRect(nsRect& aBounds, nsIFrame** aBo
 {
   *aBoundingFrame = nsnull;
 
-  nsCOMPtr<nsIAccessible> comboAccessible = GetParent();
-  if (!comboAccessible)
+  nsCOMPtr<nsIAccessible> comboAccessible;
+  GetParent(getter_AddRefs(comboAccessible));
+  if (!comboAccessible) {
     return;
-
+  }
   if (0 == (nsAccUtils::State(comboAccessible) & nsIAccessibleStates::STATE_COLLAPSED)) {
     nsHTMLSelectListAccessible::GetBoundsRect(aBounds, aBoundingFrame);
     return;
@@ -1195,10 +1259,3 @@ void nsHTMLComboboxListAccessible::GetBoundsRect(nsRect& aBounds, nsIFrame** aBo
   *aBoundingFrame = frame->GetParent();
   aBounds = (*aBoundingFrame)->GetRect();
 }
-
-// nsHTMLComboboxListAccessible. nsAccessible public mehtod
-nsIAccessible*
-nsHTMLComboboxListAccessible::GetParent()
-{
-  return mParent;
-}
diff --git a/accessible/src/html/nsHTMLSelectAccessible.h b/accessible/src/html/nsHTMLSelectAccessible.h
index 8d81a8986c03..cb3ea27bc251 100644
--- a/accessible/src/html/nsHTMLSelectAccessible.h
+++ b/accessible/src/html/nsHTMLSelectAccessible.h
@@ -130,16 +130,18 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
+  void CacheChildren();
 
-  // nsAccessible
-  virtual void CacheChildren();
-
-  // nsHTMLSelectListAccessible
-
-  /**
-   * Recursive helper for CacheChildren().
-   */
-  void CacheOptSiblings(nsIContent *aParentContent);
+  already_AddRefed<nsIAccessible>
+    AccessibleForOption(nsIAccessibilityService *aAccService,
+                        nsIContent *aContent,
+                        nsIAccessible *aLastGoodAccessible,
+                        PRInt32 *aChildCount);
+  already_AddRefed<nsIAccessible>
+    CacheOptSiblings(nsIAccessibilityService *aAccService,
+                     nsIContent *aParentContent,
+                     nsIAccessible *aLastGoodAccessible,
+                     PRInt32 *aChildCount);
 };
 
 /*
@@ -199,8 +201,7 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 };
 
 /** ------------------------------------------------------ */
@@ -235,10 +236,8 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 
-  // nsHTMLComboboxAccessible
   already_AddRefed<nsIAccessible> GetFocusedOptionAccessible();
 
 private:
@@ -260,6 +259,7 @@ public:
   virtual ~nsHTMLComboboxListAccessible() {}
 
   // nsIAccessible
+  NS_IMETHOD GetParent(nsIAccessible **aParent);
   NS_IMETHOD GetUniqueID(void **aUniqueID);
 
   // nsAccessNode
@@ -268,7 +268,6 @@ public:
   // nsAccessible
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
   virtual void GetBoundsRect(nsRect& aBounds, nsIFrame** aBoundingFrame);
-  virtual nsIAccessible* GetParent();
 };
 
 #endif
diff --git a/accessible/src/html/nsHTMLTableAccessible.cpp b/accessible/src/html/nsHTMLTableAccessible.cpp
index 64955c00ea94..6ebc01a2e313 100644
--- a/accessible/src/html/nsHTMLTableAccessible.cpp
+++ b/accessible/src/html/nsHTMLTableAccessible.cpp
@@ -455,27 +455,47 @@ NS_IMPL_ISUPPORTS_INHERITED2(nsHTMLTableAccessible, nsAccessible,
 ////////////////////////////////////////////////////////////////////////////////
 // nsHTMLTableAccessible: nsAccessible implementation
 
-void
-nsHTMLTableAccessible::CacheChildren()
+void nsHTMLTableAccessible::CacheChildren()
 {
-  nsAccessible::CacheChildren();
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+  
+  if (mAccChildCount == eChildCountUninitialized) {
+    nsAccessible::CacheChildren();
+    nsCOMPtr<nsIAccessible> captionAccessible;
+    while (NextChild(captionAccessible)) {
+      if (nsAccUtils::Role(captionAccessible) == nsIAccessibleRole::ROLE_CAPTION) {
+        nsCOMPtr<nsIAccessible> captionParentAccessible;
+        captionAccessible->GetParent(getter_AddRefs(captionParentAccessible));
+        if (captionParentAccessible != this) {
+          NS_WARNING("Should not happen: parser ensures caption is the table's child, not the tbody's");
+          return;
+        }
+        nsCOMPtr<nsIAccessible> beforeCaptionAccessible;
+        captionAccessible->GetPreviousSibling(getter_AddRefs(beforeCaptionAccessible));
+        if (beforeCaptionAccessible) {
+          // Move caption accessible so that it's the first child
+          nsRefPtr<nsAccessible> acc =
+            nsAccUtils::QueryAccessible(beforeCaptionAccessible);
 
-  // Move caption accessible so that it's the first child.
-  PRInt32 length = mChildren.Count();
-  for (PRInt32 idx = 0; idx < length; idx++) {
-    // Check for the first caption, because nsAccessibilityService ensures we
-    // don't create accessibles for the other captions, since only the first is
-    // actually visible.
+          nsCOMPtr<nsIAccessible> afterCaptionAccessible;
+          captionAccessible->GetNextSibling(getter_AddRefs(afterCaptionAccessible));
+          acc->SetNextSibling(afterCaptionAccessible);
 
-    nsIAccessible* child = mChildren.ObjectAt(idx);
-    if (nsAccUtils::Role(child) == nsIAccessibleRole::ROLE_CAPTION) {
-      if (idx == 0)
+          GetFirstChild(getter_AddRefs(afterCaptionAccessible));
+          SetFirstChild(captionAccessible);
+
+          acc = nsAccUtils::QueryAccessible(captionAccessible);
+          acc->SetNextSibling(afterCaptionAccessible);        
+        }
+        // Don't check for more captions, because nsAccessibilityService ensures
+        // we don't create accessibles for the other captions, since only the
+        // first is actually visible
         break;
-
-      nsCOMPtr<nsIAccessible> tmp = mChildren.ObjectAt(0);
-      mChildren.ReplaceObjectAt(child, 0);
-      mChildren.ReplaceObjectAt(tmp, idx);
-      break;
+      }
     }
   }
 }
diff --git a/accessible/src/html/nsHTMLTextAccessible.cpp b/accessible/src/html/nsHTMLTextAccessible.cpp
index 78fd2b8a2d75..b7c2c6dc855d 100644
--- a/accessible/src/html/nsHTMLTextAccessible.cpp
+++ b/accessible/src/html/nsHTMLTextAccessible.cpp
@@ -263,19 +263,20 @@ NS_IMETHODIMP nsHTMLLIAccessible::GetBounds(PRInt32 *x, PRInt32 *y, PRInt32 *wid
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLLIAccessible: nsAccessible protected
-
-void
-nsHTMLLIAccessible::CacheChildren()
+void nsHTMLLIAccessible::CacheChildren()
 {
-  if (mBulletAccessible) {
-    mChildren.AppendObject(mBulletAccessible);
-    mBulletAccessible->SetParent(this);
+  if (!mWeakShell || mAccChildCount != eChildCountUninitialized) {
+    return;
   }
 
-  // Cache children from subtree.
   nsAccessibleWrap::CacheChildren();
+
+  if (mBulletAccessible) {
+    mBulletAccessible->SetNextSibling(mFirstChild);
+    mBulletAccessible->SetParent(this);
+    SetFirstChild(mBulletAccessible);
+    ++ mAccChildCount;
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -331,6 +332,15 @@ nsHTMLListBulletAccessible::GetStateInternal(PRUint32 *aState, PRUint32 *aExtraS
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsHTMLListBulletAccessible::GetParent(nsIAccessible **aParent)
+{
+  NS_ENSURE_ARG_POINTER(aParent);
+
+  NS_IF_ADDREF(*aParent = mParent);
+  return NS_OK;
+}
+
 nsresult
 nsHTMLListBulletAccessible::AppendTextTo(nsAString& aText, PRUint32 aStartOffset,
                                          PRUint32 aLength)
@@ -343,12 +353,6 @@ nsHTMLListBulletAccessible::AppendTextTo(nsAString& aText, PRUint32 aStartOffset
   return NS_OK;
 }
 
-nsIAccessible*
-nsHTMLListBulletAccessible::GetParent()
-{
-  return mParent;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // nsHTMLListAccessible
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/accessible/src/html/nsHTMLTextAccessible.h b/accessible/src/html/nsHTMLTextAccessible.h
index 6d4b5c91abab..5fe7ee5d4d7f 100644
--- a/accessible/src/html/nsHTMLTextAccessible.h
+++ b/accessible/src/html/nsHTMLTextAccessible.h
@@ -106,6 +106,7 @@ public:
 
   // nsIAccessible
   NS_IMETHOD GetName(nsAString& aName);
+  NS_IMETHOD GetParent(nsIAccessible **aParent);
 
   // nsAccessNode
   virtual nsresult Shutdown();
@@ -116,8 +117,6 @@ public:
   virtual nsresult AppendTextTo(nsAString& aText, PRUint32 aStartOffset,
                                 PRUint32 aLength);
 
-  virtual nsIAccessible* GetParent();
-
 protected:
   // XXX: Ideally we'd get the bullet text directly from the bullet frame via
   // nsBulletFrame::GetListItemText(), but we'd need an interface for getting
@@ -162,10 +161,8 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();  // Include bullet accessible
 
-private:
   nsRefPtr<nsHTMLListBulletAccessible> mBulletAccessible;
 };
 
diff --git a/accessible/src/html/nsHyperTextAccessible.cpp b/accessible/src/html/nsHyperTextAccessible.cpp
index da696d9c6141..8901c5fe061e 100644
--- a/accessible/src/html/nsHyperTextAccessible.cpp
+++ b/accessible/src/html/nsHyperTextAccessible.cpp
@@ -201,44 +201,49 @@ nsHyperTextAccessible::GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState)
   return NS_OK;
 }
 
-void
-nsHyperTextAccessible::CacheChildren()
+void nsHyperTextAccessible::CacheChildren()
 {
-  PRUint32 role;
-  GetRoleInternal(&role);
-  if (role != nsIAccessibleRole::ROLE_ENTRY &&
-      role != nsIAccessibleRole::ROLE_PASSWORD_TEXT) {
-    nsAccessible::CacheChildren();
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
     return;
   }
 
-  nsCOMPtr<nsIEditor> editor;
-  GetAssociatedEditor(getter_AddRefs(editor));
-  if (!editor) {
-    nsAccessible::CacheChildren();
-    return;
-  }
+  // Special case for text entry fields, go directly to editor's root for children
+  if (mAccChildCount == eChildCountUninitialized) {
+    PRUint32 role;
+    GetRoleInternal(&role);
+    if (role != nsIAccessibleRole::ROLE_ENTRY && role != nsIAccessibleRole::ROLE_PASSWORD_TEXT) {
+      nsAccessible::CacheChildren();
+      return;
+    }
+    nsCOMPtr<nsIEditor> editor;
+    GetAssociatedEditor(getter_AddRefs(editor));
+    if (!editor) {
+      nsAccessible::CacheChildren();
+      return;
+    }
+    mAccChildCount = 0;  // Avoid reentry
+    nsCOMPtr<nsIDOMElement> editorRoot;
+    editor->GetRootElement(getter_AddRefs(editorRoot));
+    nsCOMPtr<nsIDOMNode> editorRootDOMNode = do_QueryInterface(editorRoot);
+    if (!editorRootDOMNode) {
+      return;
+    }
+    nsAccessibleTreeWalker walker(mWeakShell, editorRootDOMNode, PR_TRUE);
+    nsRefPtr<nsAccessible> prevAcc;
+    PRInt32 childCount = 0;
+    walker.GetFirstChild();
+    SetFirstChild(walker.mState.accessible);
 
-  // Special case for text entry fields, go directly to editor's root for
-  // children.
-
-  nsCOMPtr<nsIDOMElement> editorRoot;
-  editor->GetRootElement(getter_AddRefs(editorRoot));
-  nsCOMPtr<nsIDOMNode> editorRootDOMNode = do_QueryInterface(editorRoot);
-  if (!editorRootDOMNode)
-    return;
-
-  nsAccessibleTreeWalker walker(mWeakShell, editorRootDOMNode, PR_TRUE);
-
-  walker.GetFirstChild();
-  while (walker.mState.accessible) {
-    mChildren.AppendObject(walker.mState.accessible);
-
-    nsRefPtr<nsAccessible> acc =
-      nsAccUtils::QueryObject<nsAccessible>(walker.mState.accessible);
-    acc->SetParent(this);
-
-    walker.GetNextSibling();
+    while (walker.mState.accessible) {
+      ++ childCount;
+      prevAcc = nsAccUtils::QueryAccessible(walker.mState.accessible);
+      prevAcc->SetParent(this);
+      walker.GetNextSibling();
+      prevAcc->SetNextSibling(walker.mState.accessible);
+    }
+    mAccChildCount = childCount;
   }
 }
 
@@ -861,11 +866,10 @@ nsHyperTextAccessible::GetRelativeOffset(nsIPresShell *aPresShell,
     hyperTextOffset = 0;
   }  
   else if (aAmount == eSelectBeginLine) {
-    nsIAccessible *firstChild = mChildren.SafeObjectAt(0);
     // For line selection with needsStart, set start of line exactly to line break
-    if (pos.mContentOffset == 0 && firstChild &&
-        nsAccUtils::Role(firstChild) == nsIAccessibleRole::ROLE_STATICTEXT &&
-        nsAccUtils::TextLength(firstChild) == hyperTextOffset) {
+    if (pos.mContentOffset == 0 && mFirstChild && 
+        nsAccUtils::Role(mFirstChild) == nsIAccessibleRole::ROLE_STATICTEXT &&
+        nsAccUtils::TextLength(mFirstChild) == hyperTextOffset) {
       // XXX Bullet hack -- we should remove this once list bullets use anonymous content
       hyperTextOffset = 0;
     }
diff --git a/accessible/src/html/nsHyperTextAccessible.h b/accessible/src/html/nsHyperTextAccessible.h
index 3331343ddff6..81717f94eae5 100644
--- a/accessible/src/html/nsHyperTextAccessible.h
+++ b/accessible/src/html/nsHyperTextAccessible.h
@@ -86,6 +86,7 @@ public:
   virtual nsresult GetAttributesInternal(nsIPersistentProperties *aAttributes);
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
+  void CacheChildren();
 
   // Convert content offset to rendered text offset  
   static nsresult ContentToRenderedOffset(nsIFrame *aFrame, PRInt32 aContentOffset,
@@ -154,12 +155,6 @@ public:
                                       PRInt32 *aEndOffset);
 
 protected:
-
-  // nsAccessible
-  virtual void CacheChildren();
-
-  // nsHyperTextAccessible
-
   /*
    * This does the work for nsIAccessibleText::GetText[At|Before|After]Offset
    * @param aType, eGetBefore, eGetAt, eGetAfter
diff --git a/accessible/src/msaa/nsAccessibleWrap.cpp b/accessible/src/msaa/nsAccessibleWrap.cpp
index 1cb05a2f0207..a19f407935cf 100644
--- a/accessible/src/msaa/nsAccessibleWrap.cpp
+++ b/accessible/src/msaa/nsAccessibleWrap.cpp
@@ -1105,23 +1105,28 @@ __try {
   if (mEnumVARIANTPosition == kIEnumVariantDisconnected)
     return CO_E_OBJNOTCONNECTED;
 
-  PRUint32 numElementsFetched = 0;
-  for (; numElementsFetched < aNumElementsRequested;
-       numElementsFetched++, mEnumVARIANTPosition++) {
+  nsCOMPtr<nsIAccessible> traversedAcc;
+  nsresult rv = GetChildAt(mEnumVARIANTPosition, getter_AddRefs(traversedAcc));
+  if (!traversedAcc)
+    return S_FALSE;
 
-    nsIAccessible* accessible = GetChildAt(mEnumVARIANTPosition);
-    if (!accessible)
+  for (PRUint32 i = 0; i < aNumElementsRequested; i++) {
+    VariantInit(&aPVar[i]);
+
+    aPVar[i].pdispVal = NativeAccessible(traversedAcc);
+    aPVar[i].vt = VT_DISPATCH;
+    (*aNumElementsFetched)++;
+
+    nsCOMPtr<nsIAccessible> nextAcc;
+    traversedAcc->GetNextSibling(getter_AddRefs(nextAcc));
+    if (!nextAcc)
       break;
 
-    VariantInit(&aPVar[numElementsFetched]);
-
-    aPVar[numElementsFetched].pdispVal = NativeAccessible(accessible);
-    aPVar[numElementsFetched].vt = VT_DISPATCH;
+    traversedAcc = nextAcc;
   }
 
-  (*aNumElementsFetched) = numElementsFetched;
-
-  return numElementsFetched < aNumElementsRequested ? S_FALSE : S_OK;
+  mEnumVARIANTPosition += *aNumElementsFetched;
+  return (*aNumElementsFetched) < aNumElementsRequested ? S_FALSE : S_OK;
 
 } __except(nsAccessNodeWrap::FilterA11yExceptions(::GetExceptionCode(), GetExceptionInformation())) { }
   return E_FAIL;
diff --git a/accessible/src/msaa/nsHTMLWin32ObjectAccessible.cpp b/accessible/src/msaa/nsHTMLWin32ObjectAccessible.cpp
index d4e287040e7c..9885dbdbde31 100644
--- a/accessible/src/msaa/nsHTMLWin32ObjectAccessible.cpp
+++ b/accessible/src/msaa/nsHTMLWin32ObjectAccessible.cpp
@@ -49,9 +49,6 @@ nsHTMLWin32ObjectOwnerAccessible::
   nsAccessibleWrap(aNode, aShell)
 {
   mHwnd = aHwnd;
-
-  // Our only child is a nsHTMLWin32ObjectAccessible object.
-  mNativeAccessible = new nsHTMLWin32ObjectAccessible(mHwnd);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -65,6 +62,50 @@ nsHTMLWin32ObjectOwnerAccessible::Shutdown()
   return NS_OK;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// nsHTMLWin32ObjectOwnerAccessible: nsIAccessible implementation
+
+NS_IMETHODIMP
+nsHTMLWin32ObjectOwnerAccessible::GetFirstChild(nsIAccessible **aFirstChild)
+{
+  NS_ENSURE_ARG_POINTER(aFirstChild);
+  *aFirstChild = nsnull;
+
+  // Our only child is a nsHTMLWin32ObjectAccessible object.
+  if (!mNativeAccessible) {
+    if (!mHwnd)
+      return NS_OK;
+
+    mNativeAccessible = new nsHTMLWin32ObjectAccessible(mHwnd);
+    NS_ENSURE_TRUE(mNativeAccessible, NS_ERROR_OUT_OF_MEMORY);
+
+    SetFirstChild(mNativeAccessible);
+  }
+
+  *aFirstChild = mNativeAccessible;
+  NS_IF_ADDREF(*aFirstChild);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsHTMLWin32ObjectOwnerAccessible::GetLastChild(nsIAccessible **aLastChild)
+{
+  return GetFirstChild(aLastChild);
+}
+
+NS_IMETHODIMP
+nsHTMLWin32ObjectOwnerAccessible::GetChildCount(PRInt32 *aChildCount)
+{
+  NS_ENSURE_ARG_POINTER(aChildCount);
+
+  nsCOMPtr<nsIAccessible> onlyChild;
+  GetFirstChild(getter_AddRefs(onlyChild));
+  *aChildCount = onlyChild ? 1 : 0;
+  return NS_OK;
+}
+
+
 ////////////////////////////////////////////////////////////////////////////////
 // nsHTMLWin32ObjectOwnerAccessible: nsAccessible implementation
 
@@ -93,21 +134,6 @@ nsHTMLWin32ObjectOwnerAccessible::GetStateInternal(PRUint32 *aState,
   return rv;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsHTMLWin32ObjectOwnerAccessible: nsAccessible protected implementation
-
-void
-nsHTMLWin32ObjectOwnerAccessible::CacheChildren()
-{
-  if (mNativeAccessible) {
-    mChildren.AppendObject(mNativeAccessible);
-
-    nsRefPtr<nsAccessible> nativeAcc =
-      nsAccUtils::QueryObject<nsAccessible>(mNativeAccessible);
-    nativeAcc->SetParent(this);
-  }
-}
-
 
 ////////////////////////////////////////////////////////////////////////////////
 // nsHTMLWin32ObjectAccessible
diff --git a/accessible/src/msaa/nsHTMLWin32ObjectAccessible.h b/accessible/src/msaa/nsHTMLWin32ObjectAccessible.h
index 76d3cbcb2488..721586262bbe 100644
--- a/accessible/src/msaa/nsHTMLWin32ObjectAccessible.h
+++ b/accessible/src/msaa/nsHTMLWin32ObjectAccessible.h
@@ -56,6 +56,11 @@ public:
   nsHTMLWin32ObjectOwnerAccessible(nsIDOMNode* aNode, nsIWeakReference* aShell, void* aHwnd);
   virtual ~nsHTMLWin32ObjectOwnerAccessible() {}
 
+  // nsIAccessible
+  NS_IMETHOD GetFirstChild(nsIAccessible **aFirstChild);
+  NS_IMETHOD GetLastChild(nsIAccessible **aLastChild);
+  NS_IMETHOD GetChildCount(PRInt32 *aChildCount);  // Zero or one child
+
   // nsAccessNode
   virtual nsresult Shutdown();
 
@@ -64,10 +69,6 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
-
-  // nsAccessible
-  virtual void CacheChildren();
-
   void* mHwnd;
   nsCOMPtr<nsIAccessible> mNativeAccessible;
 };
diff --git a/accessible/src/xforms/nsXFormsAccessible.cpp b/accessible/src/xforms/nsXFormsAccessible.cpp
index 77973c1e6fd2..8bdb6570a092 100644
--- a/accessible/src/xforms/nsXFormsAccessible.cpp
+++ b/accessible/src/xforms/nsXFormsAccessible.cpp
@@ -105,6 +105,16 @@ nsXFormsAccessible::GetBoundChildElementValue(const nsAString& aTagName,
 void
 nsXFormsAccessible::CacheSelectChildren(nsIDOMNode *aContainerNode)
 {
+  if (!mWeakShell) {
+    // This node has been shut down
+    mAccChildCount = eChildCountUninitialized;
+    return;
+  }
+
+  if (mAccChildCount != eChildCountUninitialized)
+    return;
+
+  mAccChildCount = 0; // Avoid reentry
   nsIAccessibilityService *accService = GetAccService();
   if (!accService)
     return;
@@ -123,7 +133,7 @@ nsXFormsAccessible::CacheSelectChildren(nsIDOMNode *aContainerNode)
   children->GetLength(&length);
 
   nsCOMPtr<nsIAccessible> accessible;
-  nsRefPtr<nsAccessible> acc;
+  nsRefPtr<nsAccessible> currAccessible, prevAccessible;
 
   PRUint32 childLength = 0;
   for (PRUint32 index = 0; index < length; index++) {
@@ -133,13 +143,22 @@ nsXFormsAccessible::CacheSelectChildren(nsIDOMNode *aContainerNode)
       continue;
 
     accService->GetAttachedAccessibleFor(child, getter_AddRefs(accessible));
-    if (!accessible)
+    currAccessible = nsAccUtils::QueryAccessible(accessible);
+    if (!currAccessible)
       continue;
 
-    mChildren.AppendObject(accessible);
-    acc = nsAccUtils::QueryObject<nsAccessible>(accessible);
-    acc->SetParent(this);
+    if (childLength == 0)
+      SetFirstChild(accessible);
+
+    currAccessible->SetParent(this);
+    if (prevAccessible) {
+      prevAccessible->SetNextSibling(accessible);
+    }
+    currAccessible.swap(prevAccessible);
+    childLength++;
   }
+
+  mAccChildCount = childLength;
 }
 
 // nsIAccessible
diff --git a/accessible/src/xforms/nsXFormsFormControlsAccessible.h b/accessible/src/xforms/nsXFormsFormControlsAccessible.h
index 05dcab3a2bdb..5e9c74cf8a6e 100644
--- a/accessible/src/xforms/nsXFormsFormControlsAccessible.h
+++ b/accessible/src/xforms/nsXFormsFormControlsAccessible.h
@@ -211,10 +211,7 @@ public:
 
   // nsAccessible
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
-
-protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 };
 
 
@@ -230,10 +227,7 @@ public:
 
   // nsAccessible
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
-
-protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 };
 
 
diff --git a/accessible/src/xforms/nsXFormsWidgetsAccessible.h b/accessible/src/xforms/nsXFormsWidgetsAccessible.h
index 0bb01b25c6a1..1ae009ec92a0 100644
--- a/accessible/src/xforms/nsXFormsWidgetsAccessible.h
+++ b/accessible/src/xforms/nsXFormsWidgetsAccessible.h
@@ -98,8 +98,7 @@ public:
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
 protected:
-  // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 };
 
 #endif
diff --git a/accessible/src/xul/nsXULColorPickerAccessible.cpp b/accessible/src/xul/nsXULColorPickerAccessible.cpp
index d1d2be559e1f..d803d7d2e88c 100644
--- a/accessible/src/xul/nsXULColorPickerAccessible.cpp
+++ b/accessible/src/xul/nsXULColorPickerAccessible.cpp
@@ -166,6 +166,16 @@ nsXULColorPickerAccessible::GetRoleInternal(PRUint32 *aRole)
 void
 nsXULColorPickerAccessible::CacheChildren()
 {
+  if (IsDefunct()) {
+    mAccChildCount = eChildCountUninitialized;
+    return;   // This outer doc node has been shut down
+  }
+
+  if (mAccChildCount != eChildCountUninitialized)
+    return;
+
+  mAccChildCount = 0;  // Avoid reentry
+
   nsCOMPtr<nsIAccessible> menupopupAccessible;
   nsAccessibleTreeWalker walker(mWeakShell, mDOMNode, PR_TRUE);
   walker.GetFirstChild();
@@ -173,17 +183,23 @@ nsXULColorPickerAccessible::CacheChildren()
   while (walker.mState.accessible) {
     PRUint32 role = nsAccUtils::Role(walker.mState.accessible);
 
-    // Get an accessbile for menupopup or panel elements.
     if (role == nsIAccessibleRole::ROLE_ALERT) {
-      mChildren.AppendObject(walker.mState.accessible);
-      
-      nsRefPtr<nsAccessible> menupopupAcc =
-        nsAccUtils::QueryObject<nsAccessible>(walker.mState.accessible);
-      menupopupAcc->SetParent(this);
-
-      return;
+      // Get an accessbile for menupopup or panel elements.
+      menupopupAccessible = walker.mState.accessible;
+      break;
     }
 
     walker.GetNextSibling();
   }
+
+  if (!menupopupAccessible)
+    return;
+
+  SetFirstChild(menupopupAccessible);
+
+  nsRefPtr<nsAccessible> menupopupAcc =
+    nsAccUtils::QueryObject<nsAccessible>(menupopupAccessible);
+  menupopupAcc->SetParent(this);
+
+  mAccChildCount++;
 }
diff --git a/accessible/src/xul/nsXULFormControlAccessible.cpp b/accessible/src/xul/nsXULFormControlAccessible.cpp
index 785927be74df..1f20ceff9018 100644
--- a/accessible/src/xul/nsXULFormControlAccessible.cpp
+++ b/accessible/src/xul/nsXULFormControlAccessible.cpp
@@ -186,61 +186,78 @@ nsXULButtonAccessible::CacheChildren()
   // buttons can have button (@type="menu-button") and popup accessibles
   // (@type="menu-button" or @type="menu").
 
-  // XXX: no children until the button is menu button. Probably it's not
-  // totally correct but in general AT wants to have leaf buttons.
-  nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));
+  if (!mWeakShell) {
+    mAccChildCount = eChildCountUninitialized;
+    return;   // This outer doc node has been shut down
+  }
+  if (mAccChildCount == eChildCountUninitialized) {
+    mAccChildCount = 0;  // Avoid reentry
 
-  PRBool isMenu = content->AttrValueIs(kNameSpaceID_None,
-                                       nsAccessibilityAtoms::type,
-                                       nsAccessibilityAtoms::menu,
-                                       eCaseMatters);
+    SetFirstChild(nsnull);
 
-  PRBool isMenuButton = isMenu ?
-    PR_FALSE :
-    content->AttrValueIs(kNameSpaceID_None, nsAccessibilityAtoms::type,
-                         nsAccessibilityAtoms::menuButton, eCaseMatters);
+    // XXX: no children until the button is menu button. Probably it's not
+    // totally correct but in general AT wants to have leaf buttons.
+    nsCOMPtr<nsIContent> content(do_QueryInterface(mDOMNode));
 
-  if (!isMenu && !isMenuButton)
-    return;
+    PRBool isMenu = content->AttrValueIs(kNameSpaceID_None,
+                                         nsAccessibilityAtoms::type,
+                                         nsAccessibilityAtoms::menu,
+                                         eCaseMatters);
 
-  nsCOMPtr<nsIAccessible> buttonAccessible;
-  nsCOMPtr<nsIAccessible> menupopupAccessible;
+    PRBool isMenuButton = isMenu ?
+      PR_FALSE :
+      content->AttrValueIs(kNameSpaceID_None, nsAccessibilityAtoms::type,
+                           nsAccessibilityAtoms::menuButton, eCaseMatters);
 
-  nsAccessibleTreeWalker walker(mWeakShell, mDOMNode, PR_TRUE);
-  walker.GetFirstChild();
+    if (!isMenu && !isMenuButton)
+      return;
 
-  while (walker.mState.accessible) {
-    PRUint32 role = nsAccUtils::Role(walker.mState.accessible);
+    nsCOMPtr<nsIAccessible> buttonAccessible;
+    nsCOMPtr<nsIAccessible> menupopupAccessible;
 
-    if (role == nsIAccessibleRole::ROLE_MENUPOPUP) {
-      // Get an accessbile for menupopup or panel elements.
-      menupopupAccessible = walker.mState.accessible;
+    nsAccessibleTreeWalker walker(mWeakShell, mDOMNode, PR_TRUE);
+    walker.GetFirstChild();
 
-    } else if (isMenuButton && role == nsIAccessibleRole::ROLE_PUSHBUTTON) {
-      // Button type="menu-button" contains a real button. Get an accessible
-      // for it. Ignore dropmarker button what is placed as a last child.
-      buttonAccessible = walker.mState.accessible;
-      break;
+    while (walker.mState.accessible) {
+      PRUint32 role = nsAccUtils::Role(walker.mState.accessible);
+
+      if (role == nsIAccessibleRole::ROLE_MENUPOPUP) {
+        // Get an accessbile for menupopup or panel elements.
+        menupopupAccessible = walker.mState.accessible;
+
+      } else if (isMenuButton && role == nsIAccessibleRole::ROLE_PUSHBUTTON) {
+        // Button type="menu-button" contains a real button. Get an accessible
+        // for it. Ignore dropmarker button what is placed as a last child.
+        buttonAccessible = walker.mState.accessible;
+        break;
+      }
+
+      walker.GetNextSibling();
     }
 
-    walker.GetNextSibling();
-  }
+    if (!menupopupAccessible)
+      return;
 
-  if (!menupopupAccessible)
-    return;
+    SetFirstChild(menupopupAccessible);
 
-  mChildren.AppendObject(menupopupAccessible);
+    nsRefPtr<nsAccessible> menupopupAcc =
+      nsAccUtils::QueryObject<nsAccessible>(menupopupAccessible);
+    menupopupAcc->SetParent(this);
 
-  nsRefPtr<nsAccessible> menupopupAcc =
-    nsAccUtils::QueryObject<nsAccessible>(menupopupAccessible);
-  menupopupAcc->SetParent(this);
+    mAccChildCount++;
 
-  if (buttonAccessible) {
-    mChildren.AppendObject(buttonAccessible);
+    if (buttonAccessible) {
+      if (menupopupAcc)
+        menupopupAcc->SetNextSibling(buttonAccessible);
+      else
+        SetFirstChild(buttonAccessible);
 
-    nsRefPtr<nsAccessible> buttonAcc =
-      nsAccUtils::QueryObject<nsAccessible>(buttonAccessible);
-    buttonAcc->SetParent(this);
+      nsRefPtr<nsAccessible> buttonAcc =
+        nsAccUtils::QueryObject<nsAccessible>(buttonAccessible);
+      buttonAcc->SetParent(this);
+
+      mAccChildCount++;
+    }
   }
 }
 
diff --git a/accessible/src/xul/nsXULFormControlAccessible.h b/accessible/src/xul/nsXULFormControlAccessible.h
index 1f2d8901fcef..9ea60d213638 100644
--- a/accessible/src/xul/nsXULFormControlAccessible.h
+++ b/accessible/src/xul/nsXULFormControlAccessible.h
@@ -76,7 +76,7 @@ public:
 protected:
 
   // nsAccessible
-  virtual void CacheChildren();
+  void CacheChildren();
 
   // nsXULButtonAccessible
   PRBool ContainsMenu();
diff --git a/accessible/src/xul/nsXULTabAccessible.cpp b/accessible/src/xul/nsXULTabAccessible.cpp
index a01e7c4426a5..322dedc169f7 100644
--- a/accessible/src/xul/nsXULTabAccessible.cpp
+++ b/accessible/src/xul/nsXULTabAccessible.cpp
@@ -236,6 +236,15 @@ nsXULTabBoxAccessible::GetRoleInternal(PRUint32 *aRole)
   return NS_OK;
 }
 
+#ifdef NEVER
+/** 2 children, tabs, tabpanels */
+NS_IMETHODIMP nsXULTabBoxAccessible::GetChildCount(PRInt32 *_retval)
+{
+  *_retval = 2;
+  return NS_OK;
+}
+#endif
+
 /**
   * XUL Tabs - the s really stands for strip. this is a collection of tab objects
   */
diff --git a/accessible/src/xul/nsXULTreeAccessible.cpp b/accessible/src/xul/nsXULTreeAccessible.cpp
index e134abeaa883..1a0ce0ea225b 100644
--- a/accessible/src/xul/nsXULTreeAccessible.cpp
+++ b/accessible/src/xul/nsXULTreeAccessible.cpp
@@ -220,6 +220,83 @@ nsXULTreeAccessible::GetRoleInternal(PRUint32 *aRole)
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeAccessible: nsIAccessible implementation
 
+NS_IMETHODIMP
+nsXULTreeAccessible::GetFirstChild(nsIAccessible **aFirstChild)
+{
+  nsAccessible::GetFirstChild(aFirstChild);
+
+  // in normal case, tree's first child should be treecols, if it is not here, 
+  //   use the first row as tree's first child
+  if (*aFirstChild == nsnull) {
+    if (IsDefunct())
+      return NS_ERROR_FAILURE;
+
+    PRInt32 rowCount;
+    mTreeView->GetRowCount(&rowCount);
+    if (rowCount > 0)
+      GetTreeItemAccessible(0, aFirstChild);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeAccessible::GetLastChild(nsIAccessible **aLastChild)
+{
+  NS_ENSURE_ARG_POINTER(aLastChild);
+  *aLastChild = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  PRInt32 rowCount = 0;
+  mTreeView->GetRowCount(&rowCount);
+  if (rowCount > 0) {
+    GetTreeItemAccessible(rowCount - 1, aLastChild);
+
+    if (*aLastChild)
+      return NS_OK;
+  }
+
+  // If there is not any rows, use treecols as tree's last child.
+  return nsAccessible::GetLastChild(aLastChild);
+}
+
+NS_IMETHODIMP
+nsXULTreeAccessible::GetChildCount(PRInt32 *aChildCount)
+{
+  // tree's children count is row count + treecols count.
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsAccessible::GetChildCount(aChildCount);
+
+  if (*aChildCount != eChildCountUninitialized) {
+    PRInt32 rowCount = 0;
+    mTreeView->GetRowCount(&rowCount);
+    *aChildCount += rowCount;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeAccessible::GetChildAt(PRInt32 aChildIndex, nsIAccessible **aChild)
+{
+  NS_ENSURE_ARG_POINTER(aChild);
+  *aChild = nsnull;
+
+  PRInt32 childCount = 0;
+  nsresult rv = nsAccessible::GetChildCount(&childCount);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (aChildIndex < childCount)
+    return nsAccessible::GetChildAt(aChildIndex, aChild);
+
+  GetTreeItemAccessible(aChildIndex - childCount, aChild);
+  return *aChild ? NS_OK : NS_ERROR_INVALID_ARG;
+}
+
 NS_IMETHODIMP
 nsXULTreeAccessible::GetFocusedChild(nsIAccessible **aFocusedChild) 
 {
@@ -458,56 +535,6 @@ nsXULTreeAccessible::SelectAllSelection(PRBool *aIsMultiSelectable)
   return NS_OK;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeAccessible: nsAccessible implementation
-
-nsIAccessible*
-nsXULTreeAccessible::GetChildAt(PRUint32 aIndex)
-{
-  PRInt32 childCount = nsAccessible::GetChildCount();
-  if (childCount == -1)
-    return nsnull;
-
-  if (static_cast<PRInt32>(aIndex) < childCount)
-    return nsAccessible::GetChildAt(aIndex);
-
-  nsCOMPtr<nsIAccessible> child;
-  GetTreeItemAccessible(aIndex - childCount, getter_AddRefs(child));
-  return child;
-}
-
-PRInt32
-nsXULTreeAccessible::GetChildCount()
-{
-  // tree's children count is row count + treecols count.
-  PRInt32 childCount = nsAccessible::GetChildCount();
-  if (childCount == -1)
-    return -1;
-
-  PRInt32 rowCount = 0;
-  mTreeView->GetRowCount(&rowCount);
-  childCount += rowCount;
-
-  return childCount;
-}
-
-PRInt32
-nsXULTreeAccessible::GetIndexOf(nsIAccessible *aChild)
-{
-  if (IsDefunct())
-    return -1;
-
-  nsRefPtr<nsXULTreeItemAccessibleBase> item =
-    nsAccUtils::QueryObject<nsXULTreeItemAccessibleBase>(aChild);
-
-  // If the given child is not treeitem then it should be treecols accessible.
-  if (!item)
-    return nsAccessible::GetIndexOf(aChild);
-
-  return nsAccessible::GetChildCount() + item->GetRowIndex();
-}
-
-
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeAccessible: public implementation
 
@@ -747,6 +774,67 @@ nsXULTreeItemAccessibleBase::GetUniqueID(void **aUniqueID)
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeItemAccessibleBase: nsIAccessible implementation
 
+NS_IMETHODIMP
+nsXULTreeItemAccessibleBase::GetParent(nsIAccessible **aParent)
+{
+  NS_ENSURE_ARG_POINTER(aParent);
+  *aParent = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  if (mParent) {
+    *aParent = mParent;
+    NS_ADDREF(*aParent);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeItemAccessibleBase::GetNextSibling(nsIAccessible **aNextSibling)
+{
+  NS_ENSURE_ARG_POINTER(aNextSibling);
+  *aNextSibling = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsRefPtr<nsXULTreeAccessible> treeAcc =
+    nsAccUtils::QueryAccessibleTree(mParent);
+  NS_ENSURE_STATE(treeAcc);
+
+  PRInt32 rowCount = 0;
+  mTreeView->GetRowCount(&rowCount);
+  if (mRow + 1 >= rowCount)
+    return NS_OK;
+
+  treeAcc->GetTreeItemAccessible(mRow + 1, aNextSibling);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeItemAccessibleBase::GetPreviousSibling(nsIAccessible **aPreviousSibling)
+{
+  NS_ENSURE_ARG_POINTER(aPreviousSibling);
+  *aPreviousSibling = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsRefPtr<nsXULTreeAccessible> treeAcc =
+    nsAccUtils::QueryAccessibleTree(mParent);
+  NS_ENSURE_STATE(treeAcc);
+
+  // Get previous row accessible or tree columns accessible.
+  if (mRow > 0)
+    treeAcc->GetTreeItemAccessible(mRow - 1, aPreviousSibling);
+  else
+    treeAcc->GetFirstChild(aPreviousSibling);
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULTreeItemAccessibleBase::GetFocusedChild(nsIAccessible **aFocusedChild) 
 {
@@ -960,7 +1048,7 @@ nsXULTreeItemAccessibleBase::Shutdown()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeItemAccessibleBase: nsAccessible public methods
+// nsXULTreeItemAccessibleBase: nsAccessible implementation
 
 nsresult
 nsXULTreeItemAccessibleBase::GetAttributesInternal(nsIPersistentProperties *aAttributes)
@@ -1070,14 +1158,8 @@ nsXULTreeItemAccessibleBase::GetStateInternal(PRUint32 *aState,
   return NS_OK;
 }
 
-nsIAccessible*
-nsXULTreeItemAccessibleBase::GetParent()
-{
-  return IsDefunct() ? nsnull : mParent;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeItemAccessibleBase: nsAccessible protected methods
+// nsXULTreeItemAccessibleBase: protected implementation
 
 void
 nsXULTreeItemAccessibleBase::DispatchClickEvent(nsIContent *aContent,
@@ -1108,41 +1190,6 @@ nsXULTreeItemAccessibleBase::DispatchClickEvent(nsIContent *aContent,
     nsCoreUtils::DispatchClickEvent(mTree, mRow, column, pseudoElm);
 }
 
-nsIAccessible*
-nsXULTreeItemAccessibleBase::GetSiblingAtOffset(PRInt32 aOffset,
-                                                nsresult* aError)
-{
-  if (mRow + aOffset < 0)
-    return nsAccessible::GetSiblingAtOffset(mRow + aOffset, aError);
-
-  if (IsDefunct()) {
-    if (aError)
-      *aError = NS_ERROR_FAILURE;
-
-    return nsnull;
-  }
-
-  if (aError)
-    *aError = NS_OK; // fail peacefully
-
-  nsRefPtr<nsXULTreeAccessible> treeAcc =
-    nsAccUtils::QueryAccessibleTree(mParent);
-  if (!treeAcc)
-    return nsnull;
-
-  PRInt32 rowCount = 0;
-  mTreeView->GetRowCount(&rowCount);
-  if (mRow + aOffset >= rowCount)
-    return nsnull;
-
-  nsCOMPtr<nsIAccessible> sibling;
-  treeAcc->GetTreeItemAccessible(mRow + aOffset, getter_AddRefs(sibling));
-  return sibling;
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeItemAccessibleBase: protected implementation
-
 PRBool
 nsXULTreeItemAccessibleBase::IsExpandable()
 {
@@ -1183,6 +1230,33 @@ nsXULTreeItemAccessible(nsIDOMNode *aDOMNode, nsIWeakReference *aShell,
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeItemAccessible: nsIAccessible implementation
 
+NS_IMETHODIMP
+nsXULTreeItemAccessible::GetFirstChild(nsIAccessible **aFirstChild)
+{
+  NS_ENSURE_ARG_POINTER(aFirstChild);
+  *aFirstChild = nsnull;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeItemAccessible::GetLastChild(nsIAccessible **aLastChild)
+{
+  NS_ENSURE_ARG_POINTER(aLastChild);
+  *aLastChild = nsnull;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeItemAccessible::GetChildCount(PRInt32 *aChildCount)
+{
+  NS_ENSURE_ARG_POINTER(aChildCount);
+  *aChildCount = 0;
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULTreeItemAccessible::GetName(nsAString& aName)
 {
@@ -1264,14 +1338,6 @@ nsXULTreeItemAccessible::RowInvalidated(PRInt32 aStartColIdx,
   }
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeItemAccessible: nsAccessible protected implementation
-
-void
-nsXULTreeItemAccessible::CacheChildren()
-{
-}
-
 
 ////////////////////////////////////////////////////////////////////////////////
 //  nsXULTreeColumnsAccessible
@@ -1283,22 +1349,11 @@ nsXULTreeColumnsAccessible::
 {
 }
 
-nsIAccessible*
-nsXULTreeColumnsAccessible::GetSiblingAtOffset(PRInt32 aOffset,
-                                               nsresult* aError)
+NS_IMETHODIMP
+nsXULTreeColumnsAccessible::GetNextSibling(nsIAccessible **aNextSibling)
 {
-  if (aOffset < 0)
-    return nsXULColumnsAccessible::GetSiblingAtOffset(aOffset, aError);
-
-  if (IsDefunct()) {
-    if (aError)
-      *aError = NS_ERROR_FAILURE;
-
-    return nsnull;
-  }
-
-  if (aError)
-    *aError = NS_OK; // fail peacefully
+  NS_ENSURE_ARG_POINTER(aNextSibling);
+  *aNextSibling = nsnull;
 
   nsCOMPtr<nsITreeBoxObject> tree;
   nsCOMPtr<nsITreeView> treeView;
@@ -1309,19 +1364,16 @@ nsXULTreeColumnsAccessible::GetSiblingAtOffset(PRInt32 aOffset,
     if (treeView) {
       PRInt32 rowCount = 0;
       treeView->GetRowCount(&rowCount);
-      if (rowCount > 0 && aOffset <= rowCount) {
+      if (rowCount > 0) {
         nsRefPtr<nsXULTreeAccessible> treeAcc =
           nsAccUtils::QueryAccessibleTree(mParent);
+        NS_ENSURE_STATE(treeAcc);
 
-        if (treeAcc) {
-          nsCOMPtr<nsIAccessible> sibling;
-          treeAcc->GetTreeItemAccessible(aOffset - 1, getter_AddRefs(sibling));
-          return sibling;
-        }
+        treeAcc->GetTreeItemAccessible(0, aNextSibling);
       }
     }
   }
 
-  return nsnull;
+  return NS_OK;
 }
 
diff --git a/accessible/src/xul/nsXULTreeAccessible.h b/accessible/src/xul/nsXULTreeAccessible.h
index b772315039b5..c1f0a20d3463 100644
--- a/accessible/src/xul/nsXULTreeAccessible.h
+++ b/accessible/src/xul/nsXULTreeAccessible.h
@@ -73,6 +73,12 @@ public:
 
   // nsIAccessible
   NS_IMETHOD GetValue(nsAString& aValue);
+
+  NS_IMETHOD GetFirstChild(nsIAccessible **aFirstChild);
+  NS_IMETHOD GetLastChild(nsIAccessible **aLastChild);
+  NS_IMETHOD GetChildCount(PRInt32 *aChildCount);
+  NS_IMETHOD GetChildAt(PRInt32 aChildIndex, nsIAccessible **aChild);
+
   NS_IMETHOD GetFocusedChild(nsIAccessible **aFocusedChild);
 
   // nsIAccessibleSelectable
@@ -89,10 +95,6 @@ public:
                                    PRBool aDeepestChild,
                                    nsIAccessible **aChild);
 
-  virtual nsIAccessible* GetChildAt(PRUint32 aIndex);
-  virtual PRInt32 GetChildCount();
-  virtual PRInt32 GetIndexOf(nsIAccessible *aChild);
-
   // nsXULTreeAccessible
 
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_XULTREEACCESSIBLE_IMPL_CID)
@@ -176,6 +178,10 @@ public:
   NS_IMETHOD GetUniqueID(void **aUniqueID);
 
   // nsIAccessible
+  NS_IMETHOD GetParent(nsIAccessible **aParent);
+  NS_IMETHOD GetNextSibling(nsIAccessible **aNextSibling);
+  NS_IMETHOD GetPreviousSibling(nsIAccessible **aPreviousSibling);
+
   NS_IMETHOD GetFocusedChild(nsIAccessible **aFocusedChild);
 
   NS_IMETHOD GetBounds(PRInt32 *aX, PRInt32 *aY,
@@ -198,16 +204,10 @@ public:
   // nsAccessible
   virtual nsresult GetAttributesInternal(nsIPersistentProperties *aAttributes);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
-  virtual nsIAccessible* GetParent();
 
   // nsXULTreeItemAccessibleBase
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_XULTREEITEMBASEACCESSIBLE_IMPL_CID)
 
-  /**
-   * Return row index associated with the accessible.
-   */
-  PRInt32 GetRowIndex() const { return mRow; }
-
   /**
    * Return cell accessible for the given column. If XUL tree accessible is not
    * accessible table then return null.
@@ -226,8 +226,6 @@ protected:
 
   // nsAccessible
   virtual void DispatchClickEvent(nsIContent *aContent, PRUint32 aActionIndex);
-  virtual nsIAccessible* GetSiblingAtOffset(PRInt32 aOffset,
-                                            nsresult* aError = nsnull);
 
   // nsXULTreeItemAccessibleBase
 
@@ -255,6 +253,11 @@ public:
                           nsIAccessible *aParent, nsITreeBoxObject *aTree,
                           nsITreeView *aTreeView, PRInt32 aRow);
 
+  // nsIAccessible
+  NS_IMETHOD GetFirstChild(nsIAccessible **aFirstChild);
+  NS_IMETHOD GetLastChild(nsIAccessible **aLastChild);
+  NS_IMETHOD GetChildCount(PRInt32 *aChildCount);
+
   NS_IMETHOD GetName(nsAString& aName);
 
   // nsAccessNode
@@ -269,11 +272,6 @@ public:
   virtual void RowInvalidated(PRInt32 aStartColIdx, PRInt32 aEndColIdx);
 
 protected:
-
-  // nsAccessible
-  virtual void CacheChildren();
-
-  // nsXULTreeItemAccessible
   nsCOMPtr<nsITreeColumn> mColumn;
   nsString mCachedName;
 };
@@ -287,10 +285,8 @@ class nsXULTreeColumnsAccessible : public nsXULColumnsAccessible
 public:
   nsXULTreeColumnsAccessible(nsIDOMNode* aDOMNode, nsIWeakReference* aShell);
 
-protected:
-
-  // nsAccessible
-  nsIAccessible* GetSiblingAtOffset(PRInt32 aOffset, nsresult* aError = nsnull);
+  // nsIAccessible
+  NS_IMETHOD GetNextSibling(nsIAccessible **aNextSibling);
 };
 
 #endif
diff --git a/accessible/src/xul/nsXULTreeGridAccessible.cpp b/accessible/src/xul/nsXULTreeGridAccessible.cpp
index d369670916e0..bdcd46ee2d75 100644
--- a/accessible/src/xul/nsXULTreeGridAccessible.cpp
+++ b/accessible/src/xul/nsXULTreeGridAccessible.cpp
@@ -95,15 +95,15 @@ nsXULTreeGridAccessible::GetSummary(nsAString &aSummary)
 }
 
 NS_IMETHODIMP
-nsXULTreeGridAccessible::GetColumnCount(PRInt32 *aColumnCount)
+nsXULTreeGridAccessible::GetColumnCount(PRInt32 *acolumnCount)
 {
-  NS_ENSURE_ARG_POINTER(aColumnCount);
-  *aColumnCount = 0;
+  NS_ENSURE_ARG_POINTER(acolumnCount);
+  *acolumnCount = 0;
 
   if (IsDefunct())
     return NS_ERROR_FAILURE;
 
-  *aColumnCount = nsCoreUtils::GetSensibleColumnCount(mTree);
+  *acolumnCount = nsCoreUtils::GetSensiblecolumnCount(mTree);
   return NS_OK;
 }
 
@@ -635,6 +635,77 @@ NS_IMPL_ADDREF_INHERITED(nsXULTreeGridRowAccessible,
 NS_IMPL_RELEASE_INHERITED(nsXULTreeGridRowAccessible,
                           nsXULTreeItemAccessibleBase)
 
+////////////////////////////////////////////////////////////////////////////////
+// nsXULTreeGridRowAccessible: nsIAccessible implementation
+
+NS_IMETHODIMP
+nsXULTreeGridRowAccessible::GetFirstChild(nsIAccessible **aFirstChild)
+{
+  NS_ENSURE_ARG_POINTER(aFirstChild);
+  *aFirstChild = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsITreeColumn> column = nsCoreUtils::GetFirstSensibleColumn(mTree);
+  NS_ASSERTION(column, "No column for table grid!");
+  if (!column)
+    return NS_ERROR_FAILURE;
+
+  GetCellAccessible(column, aFirstChild);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeGridRowAccessible::GetLastChild(nsIAccessible **aLastChild)
+{
+  NS_ENSURE_ARG_POINTER(aLastChild);
+  *aLastChild = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsITreeColumn> column = nsCoreUtils::GetLastSensibleColumn(mTree);
+  NS_ASSERTION(column, "No column for table grid!");
+  if (!column)
+    return NS_ERROR_FAILURE;
+
+  GetCellAccessible(column, aLastChild);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeGridRowAccessible::GetChildCount(PRInt32 *aChildCount)
+{
+  NS_ENSURE_ARG_POINTER(aChildCount);
+  *aChildCount = 0;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  *aChildCount = nsCoreUtils::GetSensiblecolumnCount(mTree);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeGridRowAccessible::GetChildAt(PRInt32 aChildIndex,
+                                       nsIAccessible **aChild)
+{
+  NS_ENSURE_ARG_POINTER(aChild);
+  *aChild = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsITreeColumn> column =
+    nsCoreUtils::GetSensibleColumnAt(mTree, aChildIndex);
+  if (!column)
+    return NS_ERROR_INVALID_ARG;
+
+  GetCellAccessible(column, aChild);
+  return NS_OK;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeGridRowAccessible: nsAccessNode implementation
 
@@ -689,43 +760,6 @@ nsXULTreeGridRowAccessible::GetChildAtPoint(PRInt32 aX, PRInt32 aY,
   return NS_OK;
 }
 
-nsIAccessible*
-nsXULTreeGridRowAccessible::GetChildAt(PRUint32 aIndex)
-{
-  if (IsDefunct())
-    return nsnull;
-
-  nsCOMPtr<nsITreeColumn> column =
-    nsCoreUtils::GetSensibleColumnAt(mTree, aIndex);
-  if (!column)
-    return nsnull;
-
-  nsCOMPtr<nsIAccessible> cell;
-  GetCellAccessible(column, getter_AddRefs(cell));
-  return cell;
-}
-
-PRInt32
-nsXULTreeGridRowAccessible::GetChildCount()
-{
-  if (IsDefunct())
-    return -1;
-
-  return nsCoreUtils::GetSensibleColumnCount(mTree);
-}
-
-PRInt32
-nsXULTreeGridRowAccessible::GetIndexOf(nsIAccessible *aChild)
-{
-  if (IsDefunct())
-    return -1;
-
-  nsRefPtr<nsXULTreeGridCellAccessible> cell =
-    nsAccUtils::QueryObject<nsXULTreeGridCellAccessible>(aChild);
-
-  return cell ? cell->GetColumnIndex() : -1;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeGridRowAccessible: nsXULTreeItemAccessibleBase implementation
 
@@ -784,13 +818,6 @@ nsXULTreeGridRowAccessible::RowInvalidated(PRInt32 aStartColIdx,
   }
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeGridRowAccessible: nsAccessible protected implementation
-
-void
-nsXULTreeGridRowAccessible::CacheChildren()
-{
-}
 
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeGridCellAccessible
@@ -830,6 +857,64 @@ nsXULTreeGridCellAccessible::GetUniqueID(void **aUniqueID)
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeGridCellAccessible: nsIAccessible implementation
 
+NS_IMETHODIMP
+nsXULTreeGridCellAccessible::GetParent(nsIAccessible **aParent)
+{
+  NS_ENSURE_ARG_POINTER(aParent);
+  *aParent = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  if (mParent) {
+    *aParent = mParent;
+    NS_ADDREF(*aParent);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeGridCellAccessible::GetNextSibling(nsIAccessible **aNextSibling)
+{
+  NS_ENSURE_ARG_POINTER(aNextSibling);
+  *aNextSibling = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsITreeColumn> nextColumn =
+    nsCoreUtils::GetNextSensibleColumn(mColumn);
+  if (!nextColumn)
+    return NS_OK;
+
+  nsRefPtr<nsXULTreeItemAccessibleBase> rowAcc =
+    nsAccUtils::QueryObject<nsXULTreeItemAccessibleBase>(mParent);
+  rowAcc->GetCellAccessible(nextColumn, aNextSibling);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsXULTreeGridCellAccessible::GetPreviousSibling(nsIAccessible **aPreviousSibling)
+{
+  NS_ENSURE_ARG_POINTER(aPreviousSibling);
+  *aPreviousSibling = nsnull;
+
+  if (IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsITreeColumn> nextColumn =
+    nsCoreUtils::GetPreviousSensibleColumn(mColumn);
+  if (!nextColumn)
+    return NS_OK;
+
+  nsRefPtr<nsXULTreeItemAccessibleBase> rowAcc =
+    nsAccUtils::QueryObject<nsXULTreeItemAccessibleBase>(mParent);
+  rowAcc->GetCellAccessible(nextColumn, aPreviousSibling);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULTreeGridCellAccessible::GetFocusedChild(nsIAccessible **aFocusedChild) 
 {
@@ -1134,7 +1219,7 @@ nsXULTreeGridCellAccessible::Init()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeGridCellAccessible: nsAccessible public implementation
+// nsXULTreeGridCellAccessible: nsAccessible implementation
 
 nsresult
 nsXULTreeGridCellAccessible::GetAttributesInternal(nsIPersistentProperties *aAttributes)
@@ -1222,12 +1307,6 @@ nsXULTreeGridCellAccessible::GetStateInternal(PRUint32 *aStates,
   return NS_OK;
 }
 
-nsIAccessible*
-nsXULTreeGridCellAccessible::GetParent()
-{
-  return IsDefunct() ? nsnull : mParent;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // nsXULTreeGridCellAccessible: public implementation
 
@@ -1273,46 +1352,7 @@ nsXULTreeGridCellAccessible::CellInvalidated()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeGridCellAccessible: nsAccessible protected implementation
-
-nsIAccessible*
-nsXULTreeGridCellAccessible::GetSiblingAtOffset(PRInt32 aOffset,
-                                                nsresult* aError)
-{
-  if (IsDefunct()) {
-    if (aError)
-      *aError = NS_ERROR_FAILURE;
-
-    return nsnull;
-  }
-
-  if (aError)
-    *aError = NS_OK; // fail peacefully
-
-  nsCOMPtr<nsITreeColumn> columnAtOffset(mColumn), column;
-  if (aOffset < 0) {
-    for (PRInt32 index = aOffset; index < 0 && columnAtOffset; index++) {
-      column = nsCoreUtils::GetPreviousSensibleColumn(columnAtOffset);
-      column.swap(columnAtOffset);
-    }
-  } else {
-    for (PRInt32 index = aOffset; index > 0 && columnAtOffset; index--) {
-      column = nsCoreUtils::GetNextSensibleColumn(columnAtOffset);
-      column.swap(columnAtOffset);
-    }
-  }
-
-  if (!columnAtOffset)
-    return nsnull;
-
-  nsRefPtr<nsXULTreeItemAccessibleBase> rowAcc =
-    nsAccUtils::QueryObject<nsXULTreeItemAccessibleBase>(mParent);
-
-  nsCOMPtr<nsIAccessible> sibling;
-  rowAcc->GetCellAccessible(columnAtOffset, getter_AddRefs(sibling));
-
-  return sibling;
-}
+// nsXULTreeGridCellAccessible: protected implementation
 
 void
 nsXULTreeGridCellAccessible::DispatchClickEvent(nsIContent *aContent,
@@ -1324,9 +1364,6 @@ nsXULTreeGridCellAccessible::DispatchClickEvent(nsIContent *aContent,
   nsCoreUtils::DispatchClickEvent(mTree, mRow, mColumn);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// nsXULTreeGridCellAccessible: protected implementation
-
 PRBool
 nsXULTreeGridCellAccessible::IsEditable() const
 {
diff --git a/accessible/src/xul/nsXULTreeGridAccessible.h b/accessible/src/xul/nsXULTreeGridAccessible.h
index 14f4f7c5a6ae..5451d99e7033 100644
--- a/accessible/src/xul/nsXULTreeGridAccessible.h
+++ b/accessible/src/xul/nsXULTreeGridAccessible.h
@@ -86,6 +86,12 @@ public:
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(nsXULTreeGridRowAccessible,
                                            nsAccessible)
 
+  // nsIAccessible
+  NS_IMETHOD GetFirstChild(nsIAccessible **aFirstChild);
+  NS_IMETHOD GetLastChild(nsIAccessible **aLastChild);
+  NS_IMETHOD GetChildCount(PRInt32 *aChildCount);
+  NS_IMETHOD GetChildAt(PRInt32 aChildIndex, nsIAccessible **aChild);
+
   // nsAccessNode
   virtual nsresult Shutdown();
 
@@ -95,20 +101,11 @@ public:
                                    PRBool aDeepestChild,
                                    nsIAccessible **aChild);
 
-  virtual nsIAccessible* GetChildAt(PRUint32 aIndex);
-  virtual PRInt32 GetChildCount();
-  virtual PRInt32 GetIndexOf(nsIAccessible *aChild);
-
   // nsXULTreeItemAccessibleBase
   virtual void GetCellAccessible(nsITreeColumn *aColumn, nsIAccessible **aCell);
   virtual void RowInvalidated(PRInt32 aStartColIdx, PRInt32 aEndColIdx);
 
 protected:
-
-  // nsAccessible
-  virtual void CacheChildren();
-
-  // nsXULTreeItemAccessibleBase
   nsAccessNodeHashtable mAccessNodeCache;
 };
 
@@ -142,6 +139,10 @@ public:
   NS_IMETHOD GetUniqueID(void **aUniqueID);
 
   // nsIAccessible
+  NS_IMETHOD GetParent(nsIAccessible **aParent);
+  NS_IMETHOD GetNextSibling(nsIAccessible **aNextSibling);
+  NS_IMETHOD GetPreviousSibling(nsIAccessible **aPrevSibling);
+
   NS_IMETHOD GetFocusedChild(nsIAccessible **aFocusedChild);
 
   NS_IMETHOD GetName(nsAString& aName);
@@ -164,8 +165,6 @@ public:
   virtual nsresult GetRoleInternal(PRUint32 *aRole);
   virtual nsresult GetStateInternal(PRUint32 *aState, PRUint32 *aExtraState);
 
-  virtual nsIAccessible* GetParent();
-
   // nsXULTreeGridCellAccessible
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_XULTREEGRIDCELLACCESSIBLE_IMPL_CID)
 
@@ -182,8 +181,6 @@ public:
 
 protected:
   // nsAccessible
-  virtual nsIAccessible* GetSiblingAtOffset(PRInt32 aOffset,
-                                            nsresult* aError = nsnull);
   virtual void DispatchClickEvent(nsIContent *aContent, PRUint32 aActionIndex);
 
   // nsXULTreeGridCellAccessible
diff --git a/accessible/tests/mochitest/Makefile.in b/accessible/tests/mochitest/Makefile.in
index 0ce639c81016..ef0d1e949c6d 100644
--- a/accessible/tests/mochitest/Makefile.in
+++ b/accessible/tests/mochitest/Makefile.in
@@ -108,13 +108,14 @@ _TEST_FILES =\
 		test_groupattrs.xul \
 		test_groupattrs.html \
 		test_invalidate_accessnode.html \
+		test_invalidate_elmli.html \
 		test_name.html \
 		test_name.xul \
 		test_name_button.html \
 		test_name_link.html \
 		test_name_markup.html \
-		test_name_nsApplicationAcc.html \
 		test_name_nsRootAcc.xul \
+		test_nsIAccessible_applicationAccessible.html \
 	$(warning test_nsIAccessible_comboboxes.xul temporarily disabled) \
  		test_nsIAccessible_selects.html \
 		test_nsIAccessible_focus.html \
diff --git a/accessible/tests/mochitest/common.js b/accessible/tests/mochitest/common.js
index 8712c76e9c47..523457fb6809 100644
--- a/accessible/tests/mochitest/common.js
+++ b/accessible/tests/mochitest/common.js
@@ -270,35 +270,6 @@ function getRootAccessible(aAccOrElmOrID)
   return null;
 }
 
-/**
- * Return application accessible.
- */
-function getApplicationAccessible()
-{
-  var acc = getAccessible(document), parent = null;
-  while (acc) {
-
-    try {
-      parent = acc.parent;
-    } catch (e) {
-      ok(false, "Can't get a parent for " + prettyName(acc));
-      return null;
-    }
-
-    if (!parent) {
-      if (acc.role == ROLE_APP_ROOT)
-        return acc;
-
-      ok(false, "No application accessible!");
-      return null;
-    }
-
-    acc = parent;
-  }
-
-  return null;
-}
-
 /**
  * Run through accessible tree of the given identifier so that we ensure
  * accessible tree is created.
@@ -385,12 +356,6 @@ function testAccessibleTree(aAccOrElmOrID, aAccTree)
         try { parent = child.parent; } catch (e) {}
         is(parent, acc, "Wrong parent of " + prettyName(child));
 
-        // nsIAccessible::indexInParent
-        var indexInParent = -1;
-        try { indexInParent = child.indexInParent; } catch(e) {}
-        is(indexInParent, i,
-           "Wrong index in parent of " + prettyName(child));
-
         // nsIAccessible::nextSibling
         var expectedNextSibling = (i < childCount - 1) ?
           children.queryElementAt(i + 1, nsIAccessible) : null;
@@ -414,84 +379,6 @@ function testAccessibleTree(aAccOrElmOrID, aAccTree)
   }
 }
 
-/**
- * Test accessible tree for defunct accessible.
- *
- * @param  aAcc       [in] the defunct accessible
- * @param  aNodeOrId  [in] the DOM node identifier for the defunct accessible
- */
-function testDefunctAccessible(aAcc, aNodeOrId)
-{
-  if (aNodeOrId)
-    ok(!isAccessible(aNodeOrId),
-       "Accessible for " + aNodeOrId + " wasn't properly shut down!");
-
-  var msg = " doesn't fail for shut down accessible " + prettyName(aNodeOrId) + "!";
-
-  // firstChild
-  var success = false;
-  try {
-    aAcc.firstChild;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE)
-  }
-  ok(success, "firstChild" + msg);
-
-  // lastChild
-  success = false;
-  try {
-    aAcc.lastChild;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE)
-  }
-  ok(success, "lastChild" + msg);
-
-  // childCount
-  success = false;
-  try {
-    aAcc.childCount;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE)
-  }
-  ok(success, "childCount" + msg);
-
-  // children
-  success = false;
-  try {
-    aAcc.children;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE)
-  }
-  ok(success, "children" + msg);
-
-  // nextSibling
-  success = false;
-  try {
-    aAcc.nextSibling;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE);
-  }
-  ok(success, "nextSibling" + msg);
-
-  // previousSibling
-  success = false;
-  try {
-    aAcc.previousSibling;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE);
-  }
-  ok(success, "previousSibling" + msg);
-
-  // parent
-  success = false;
-  try {
-    aAcc.parent;
-  } catch (e) {
-    success = (e.result == Components.results.NS_ERROR_FAILURE);
-  }
-  ok(success, "parent" + msg);
-}
-
 
 /**
  * Convert role to human readable string.
diff --git a/accessible/tests/mochitest/role.js b/accessible/tests/mochitest/role.js
index eef1db4a1948..8caa499b0261 100644
--- a/accessible/tests/mochitest/role.js
+++ b/accessible/tests/mochitest/role.js
@@ -8,7 +8,6 @@ const ROLE_AUTOCOMPLETE = nsIAccessibleRole.ROLE_AUTOCOMPLETE;
 const ROLE_BUTTONDROPDOWNGRID = nsIAccessibleRole.ROLE_BUTTONDROPDOWNGRID;
 const ROLE_CAPTION = nsIAccessibleRole.ROLE_CAPTION;
 const ROLE_CELL = nsIAccessibleRole.ROLE_CELL;
-const ROLE_CHECKBUTTON = nsIAccessibleRole.ROLE_CHECKBUTTON;
 const ROLE_CHROME_WINDOW = nsIAccessibleRole.ROLE_CHROME_WINDOW;
 const ROLE_COMBOBOX = nsIAccessibleRole.ROLE_COMBOBOX;
 const ROLE_COMBOBOX_LIST = nsIAccessibleRole.ROLE_COMBOBOX_LIST;
@@ -41,11 +40,9 @@ const ROLE_PARENT_MENUITEM = nsIAccessibleRole.ROLE_PARENT_MENUITEM;
 const ROLE_PASSWORD_TEXT = nsIAccessibleRole.ROLE_PASSWORD_TEXT;
 const ROLE_PROGRESSBAR = nsIAccessibleRole.ROLE_PROGRESSBAR;
 const ROLE_PUSHBUTTON = nsIAccessibleRole.ROLE_PUSHBUTTON;
-const ROLE_RADIOBUTTON = nsIAccessibleRole.ROLE_RADIOBUTTON;
 const ROLE_ROW = nsIAccessibleRole.ROLE_ROW;
 const ROLE_ROWHEADER = nsIAccessibleRole.ROLE_ROWHEADER;
 const ROLE_SECTION = nsIAccessibleRole.ROLE_SECTION;
-const ROLE_SEPARATOR = nsIAccessibleRole.ROLE_SEPARATOR;
 const ROLE_SLIDER = nsIAccessibleRole.ROLE_SLIDER;
 const ROLE_STATICTEXT = nsIAccessibleRole.ROLE_STATICTEXT;
 const ROLE_TABLE = nsIAccessibleRole.ROLE_TABLE;
@@ -53,7 +50,6 @@ const ROLE_TEXT_CONTAINER = nsIAccessibleRole.ROLE_TEXT_CONTAINER;
 const ROLE_TEXT_LEAF = nsIAccessibleRole.ROLE_TEXT_LEAF;
 const ROLE_TOGGLE_BUTTON = nsIAccessibleRole.ROLE_TOGGLE_BUTTON;
 const ROLE_TREE_TABLE = nsIAccessibleRole.ROLE_TREE_TABLE;
-const ROLE_WHITESPACE = nsIAccessibleRole.ROLE_WHITESPACE;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Public methods
diff --git a/accessible/tests/mochitest/test_events_doc.html b/accessible/tests/mochitest/test_events_doc.html
index 8139930c9e5b..b1752c05c50f 100644
--- a/accessible/tests/mochitest/test_events_doc.html
+++ b/accessible/tests/mochitest/test_events_doc.html
@@ -47,12 +47,7 @@
       var docAcc = getAccessible(document);
       while (docAcc) {
         this.mRootAcc = docAcc;
-        try {
-          docAcc = docAcc.parent;
-        } catch (e) {
-          ok(false, "Can't get parent for " + prettyName(docAcc));
-          throw e;
-        }
+        docAcc = docAcc.parent;
       }
 
       this.eventSeq = [
diff --git a/accessible/tests/mochitest/tree/test_list_invalidate.html b/accessible/tests/mochitest/test_invalidate_elmli.html
similarity index 70%
rename from accessible/tests/mochitest/tree/test_list_invalidate.html
rename to accessible/tests/mochitest/test_invalidate_elmli.html
index eee99bed59d8..a89b5ef0a518 100644
--- a/accessible/tests/mochitest/tree/test_list_invalidate.html
+++ b/accessible/tests/mochitest/test_invalidate_elmli.html
@@ -23,6 +23,47 @@
     ////////////////////////////////////////////////////////////////////////////
     // Helpers
 
+    function testDefunctAccessible(aAcc, aNodeOrId)
+    {
+      if (aNodeOrId)
+        ok(!isAccessible(aNodeOrId),
+           "Accessible for " + aNodeOrId + " wasn't properly shut down!");
+
+      ok(!aAcc.firstChild, "There is first child for shut down accessible!");
+      ok(!aAcc.lastChild, "There is last child for shut down accessible!");
+      ok(!aAcc.children.length, "There are children for shut down accessible!");
+
+      // nextSibling
+      var success = false;
+      try {
+        aAcc.nextSibling;
+      } catch (e) {
+        success = (e.result == Components.results.NS_ERROR_FAILURE);
+      }
+
+      ok(success, "There is next sibling for shut down accessible!");
+
+      // previousSibling
+      var success = false;
+      try {
+        aAcc.previousSibling;
+      } catch (e) {
+        success = (e.result == Components.results.NS_ERROR_FAILURE);
+      }
+
+      ok(success, "There is previous sibling for shut down accessible!");
+
+      // parent
+      var success = false;
+      try {
+        aAcc.parent;
+      } catch (e) {
+        success = (e.result == Components.results.NS_ERROR_FAILURE);
+      }
+
+      ok(success, "There is parent for shut down accessible!");
+    }
+
     function testLiAccessibleTree()
     {
       // Test accessible tree.
@@ -60,14 +101,12 @@
       this.onProcessed = function hideProcessor_onProcessed()
       {
         window.setTimeout(
-          function(aLiAcc, aLiNode, aBulletAcc)
+          function(aArg1, aArg2)
           {
-            testDefunctAccessible(aLiAcc, aLiNode);
-            testDefunctAccessible(aBulletAcc);
-
+            testDefunctAccessible(aArg1, aArg2);
             gSequence.processNext();
           },
-          0, this.li, this.liNode, this.bullet
+          0, this.li, this.liNode
         );
       }
     };
diff --git a/accessible/tests/mochitest/test_name_nsApplicationAcc.html b/accessible/tests/mochitest/test_nsIAccessible_applicationAccessible.html
similarity index 86%
rename from accessible/tests/mochitest/test_name_nsApplicationAcc.html
rename to accessible/tests/mochitest/test_nsIAccessible_applicationAccessible.html
index 3686dd523a5a..bf86b66e320d 100644
--- a/accessible/tests/mochitest/test_name_nsApplicationAcc.html
+++ b/accessible/tests/mochitest/test_nsIAccessible_applicationAccessible.html
@@ -7,20 +7,22 @@
   <script type="application/javascript" 
           src="chrome://mochikit/content/MochiKit/packed.js"></script>
   <script type="application/javascript" 
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js">
+   </script>
   <script type="application/javascript" 
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript" 
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
+          src="chrome://mochikit/content/a11y/accessible/common.js" ></script>
 
   <script type="application/javascript">
     function doTest()
     {
-        var accessible = getApplicationAccessible();
+        var accessible = getAccessible(document);
+        while (accessible && accessible.parent) {
+            accessible = accessible.parent;
+        }
+
         if (!accessible) {
-          SimpleTest.finish();
-          return;
+            SimpleTest.finish();
+            return;
         }
 
         var bundleServ = Components.classes["@mozilla.org/intl/stringbundle;1"]
diff --git a/accessible/tests/mochitest/tree/Makefile.in b/accessible/tests/mochitest/tree/Makefile.in
index 07af5d5268b1..a73628b0f5d5 100644
--- a/accessible/tests/mochitest/tree/Makefile.in
+++ b/accessible/tests/mochitest/tree/Makefile.in
@@ -50,18 +50,10 @@ _TEST_FILES =\
 		test_colorpicker.xul \
 		test_combobox.xul \
 		test_filectrl.html \
-		test_formctrl.html \
-		test_formctrl.xul \
-		test_groupbox.xul \
-		test_iframe.html \
-		test_img.html \
-		test_list.html \
-		test_list_invalidate.html \
 		test_media.html \
 		test_menu.xul \
 		test_select.html \
 		test_tree.xul \
-		test_txtcntr.html \
 		test_txtctrl.html \
 		$(NULL)
 
diff --git a/accessible/tests/mochitest/tree/test_formctrl.html b/accessible/tests/mochitest/tree/test_formctrl.html
deleted file mode 100644
index e65205b3ab3a..000000000000
--- a/accessible/tests/mochitest/tree/test_formctrl.html
+++ /dev/null
@@ -1,83 +0,0 @@
-<!DOCTYPE html>
-<html>
-
-<head>
-  <title>HTML form controls tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/MochiKit/packed.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
-
-  <script type="application/javascript">
-    function doTest()
-    {
-      // input@type="checkbox"
-      var accTree = {
-        role: ROLE_CHECKBUTTON,
-        children: [ ]
-      };
-
-      testAccessibleTree("checkbox", accTree);
-
-      // input@type="radio"
-      accTree = {
-        role: ROLE_RADIOBUTTON,
-        children: [ ]
-      };
-
-      testAccessibleTree("radio", accTree);
-
-      // input@type="button" and button
-      accTree = {
-        role: ROLE_PUSHBUTTON,
-        children: [ ]
-      };
-
-      testAccessibleTree("btn1", accTree);
-
-      // button
-      accTree = {
-        role: ROLE_PUSHBUTTON,
-        children: [
-          {
-            role: ROLE_TEXT_LEAF
-          }
-        ]
-      };
-
-      testAccessibleTree("btn2", accTree);
-
-      SimpleTest.finish();
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  </script>
-</head>
-<body>
-
-  <a target="_blank"
-     title="Fix O(n^2) access to all the children of a container"
-     href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045">
-    Mozilla Bug 342045
-  </a>
-  <p id="display"></p>
-  <div id="content" style="display: none"></div>
-  <pre id="test">
-  </pre>
-
-  <input type="checkbox" id="checkbox">
-  <input type="radio" id="radio">
-  <input type="button" value="button" id="btn1">
-  <button id="btn2">button</button>
-
-</body>
-</html>
diff --git a/accessible/tests/mochitest/tree/test_formctrl.xul b/accessible/tests/mochitest/tree/test_formctrl.xul
deleted file mode 100644
index 825a16be1241..000000000000
--- a/accessible/tests/mochitest/tree/test_formctrl.xul
+++ /dev/null
@@ -1,83 +0,0 @@
-<?xml version="1.0"?>
-<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
-<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css"
-                 type="text/css"?>
-
-<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        title="Accessible XUL checkbox and radio hierarchy tests">
-
-  <script type="application/javascript" 
-          src="chrome://mochikit/content/MochiKit/packed.js" />
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js" />
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js" />
-
-  <script type="application/javascript">
-  <![CDATA[
-    ////////////////////////////////////////////////////////////////////////////
-    // Test
-
-    function doTest()
-    {
-      // checkbox
-      var accTree = {
-        role: ROLE_CHECKBUTTON,
-        children: [ ]
-      };
-
-      testAccessibleTree("checkbox", accTree);
-
-      // radiogroup
-      accTree = {
-        role: ROLE_GROUPING,
-        children: [
-          {
-            role: ROLE_RADIOBUTTON,
-            children: [ ]
-          },
-          {
-            role: ROLE_RADIOBUTTON,
-            children: [ ]
-          }
-        ]
-      };
-
-      testAccessibleTree("radiogroup", accTree);
-
-      SimpleTest.finish()
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  ]]>
-  </script>
-
-  <hbox flex="1" style="overflow: auto;">
-    <body xmlns="http://www.w3.org/1999/xhtml">
-      <a target="_blank"
-         href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045"
-         title="Fix O(n^2) access to all the children of a container">
-        Mozilla Bug 342045
-      </a><br/>
-      <p id="display"></p>
-      <div id="content" style="display: none">
-      </div>
-      <pre id="test">
-      </pre>
-    </body>
-
-    <vbox flex="1">
-      <checkbox id="checkbox" label="checkbox"/>
-      <radiogroup id="radiogroup">
-        <radio label="radio1"/>
-        <radio label="radio2"/>
-      </radiogroup>
-    </vbox>
-  </hbox>
-
-</window>
-
diff --git a/accessible/tests/mochitest/tree/test_groupbox.xul b/accessible/tests/mochitest/tree/test_groupbox.xul
deleted file mode 100644
index 407664c7903a..000000000000
--- a/accessible/tests/mochitest/tree/test_groupbox.xul
+++ /dev/null
@@ -1,73 +0,0 @@
-<?xml version="1.0"?>
-<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
-<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css"
-                 type="text/css"?>
-
-<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        title="Accessible XUL groupbox hierarchy tests">
-
-  <script type="application/javascript" 
-          src="chrome://mochikit/content/MochiKit/packed.js" />
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js" />
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js" />
-
-  <script type="application/javascript">
-  <![CDATA[
-    ////////////////////////////////////////////////////////////////////////////
-    // Test
-
-    function doTest()
-    {
-      accTree = {
-        role: ROLE_GROUPING,
-        children: [
-          {
-            role: ROLE_LABEL,
-            children: [ ]
-          },
-          {
-            role: ROLE_CHECKBUTTON,
-            children: [ ]
-          }
-        ]
-      };
-
-      testAccessibleTree("groupbox", accTree);
-
-      SimpleTest.finish()
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  ]]>
-  </script>
-
-  <hbox flex="1" style="overflow: auto;">
-    <body xmlns="http://www.w3.org/1999/xhtml">
-      <a target="_blank"
-         href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045"
-         title="Fix O(n^2) access to all the children of a container">
-        Mozilla Bug 342045
-      </a><br/>
-      <p id="display"></p>
-      <div id="content" style="display: none">
-      </div>
-      <pre id="test">
-      </pre>
-    </body>
-
-    <vbox flex="1">
-      <groupbox id="groupbox">
-        <caption label="Some caption" />
-        <checkbox label="some checkbox label" />
-    </groupbox>
-    </vbox>
-  </hbox>
-
-</window>
-
diff --git a/accessible/tests/mochitest/tree/test_iframe.html b/accessible/tests/mochitest/tree/test_iframe.html
deleted file mode 100644
index 6ef2e82585cd..000000000000
--- a/accessible/tests/mochitest/tree/test_iframe.html
+++ /dev/null
@@ -1,54 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <title>Outer document accessible tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/MochiKit/packed.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
-
-  <script type="application/javascript">
-    function doTest()
-    {
-      var accTree = {
-        role: ROLE_INTERNAL_FRAME,
-        children: [
-          {
-            role: ROLE_DOCUMENT
-          }
-        ]
-      };
-
-      testAccessibleTree("iframe", accTree);
-
-      SimpleTest.finish();
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  </script>
-</head>
-<body>
-
-  <a target="_blank"
-     title="Fix O(n^2) access to all the children of a container"
-     href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045">
-    Mozilla Bug 342045
-  </a>
-  <p id="display"></p>
-  <div id="content" style="display: none"></div>
-  <pre id="test">
-  </pre>
-
-  <iframe id="iframe" src="about:mozilla">
-
-</body>
-</html>
diff --git a/accessible/tests/mochitest/tree/test_img.html b/accessible/tests/mochitest/tree/test_img.html
deleted file mode 100644
index 0022b4d6808c..000000000000
--- a/accessible/tests/mochitest/tree/test_img.html
+++ /dev/null
@@ -1,79 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <title>HTML img tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/MochiKit/packed.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
-
-  <script type="application/javascript">
-    function doTest()
-    {
-      // image map
-      var accTree = {
-        role: ROLE_IMAGE_MAP,
-        children: [
-          {
-            role: ROLE_LINK,
-            children: []
-          },
-          {
-            role: ROLE_LINK,
-            children: []
-          }
-        ]
-      };
-
-      testAccessibleTree("imgmap", accTree);
-
-      // img
-      accTree = {
-        role: ROLE_GRAPHIC,
-        children: []
-      };
-
-      testAccessibleTree("img", accTree);
-
-      SimpleTest.finish();
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  </script>
-</head>
-<body>
-
-  <a target="_blank"
-     title="Fix O(n^2) access to all the children of a container"
-     href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045">
-    Mozilla Bug 342045
-  </a>
-  <p id="display"></p>
-  <div id="content" style="display: none"></div>
-  <pre id="test">
-  </pre>
-
-  <map name="atoz_map">
-    <area href="http://www.bbc.co.uk/radio4/atoz/index.shtml#b"
-          coords="17,0,30,14" alt="b" shape="rect">
-    <area href="http://www.bbc.co.uk/radio4/atoz/index.shtml#a"
-          coords="0,0,13,14" alt="a" shape="rect">
-  </map>
-
-  <img id="imgmap" width="447" height="15"
-       usemap="#atoz_map"
-       src="chrome://mochikit/content/a11y/accessible/letters.gif">
-
-  <img id="img" src="chrome://mochikit/content/a11y/accessible/moz.png">
-
-</body>
-</html>
diff --git a/accessible/tests/mochitest/tree/test_list.html b/accessible/tests/mochitest/tree/test_list.html
deleted file mode 100644
index 48f2d2c2cac0..000000000000
--- a/accessible/tests/mochitest/tree/test_list.html
+++ /dev/null
@@ -1,105 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <title>HTML ul/li element tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/MochiKit/packed.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
-
-  <script type="application/javascript">
-    function listItemTree(aBulletText, aName, aSubtree)
-    {
-      var obj = {
-        role: ROLE_LISTITEM,
-        children: [
-          {
-            role: ROLE_STATICTEXT,
-            name: aBulletText
-          },
-          {
-            role: ROLE_TEXT_LEAF,
-            name: aName
-          }
-        ]
-      };
-
-      if (aSubtree)
-        obj.children.push(aSubtree);
-
-      return obj;
-    }
-
-    function doTest()
-    {
-      var bulletText = String.fromCharCode(0x2022) + " ";
-
-      // list1
-      var accTree = {
-        role: ROLE_LIST,
-        children: [
-          new listItemTree(bulletText, "Oranges"),
-          new listItemTree(bulletText, "Apples"),
-          new listItemTree(bulletText, "Bananas")
-        ]
-      };
-
-      testAccessibleTree("list1", accTree);
-
-      // list2
-      accTree = {
-        role: ROLE_LIST,
-        children: [
-          new listItemTree("1. ", "Oranges"),
-          new listItemTree("2. ", "Apples"),
-          new listItemTree("3. ", "Bananas", accTree)
-        ]
-      };
-
-      testAccessibleTree("list2", accTree);
-
-      SimpleTest.finish();
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  </script>
-</head>
-<body>
-
-  <a target="_blank"
-     title="Fix O(n^2) access to all the children of a container"
-     href="https://bugzilla.mozilla.org/show_bug.cgi?id=342045">
-    Mozilla Bug 342045
-  </a>
-  <p id="display"></p>
-  <div id="content" style="display: none"></div>
-  <pre id="test">
-  </pre>
-
-  <ul id="list1">
-    <li id="li1">Oranges</li>
-    <li id="li2">Apples</li>
-    <li id="li3">Bananas</li>
-  </ul>
-
-  <ol id="list2">
-    <li id="li4">Oranges</li>
-    <li id="li5">Apples</li>
-    <li id="li6">Bananas<ul>
-        <li id="n_li4">Oranges</li>
-        <li id="n_li5">Apples</li>
-        <li id="n_li6">Bananas</li>
-      </ul>
-    </li>
-  </ol>
-</body>
-</html>
diff --git a/accessible/tests/mochitest/tree/test_txtcntr.html b/accessible/tests/mochitest/tree/test_txtcntr.html
deleted file mode 100644
index 56825ced1e7b..000000000000
--- a/accessible/tests/mochitest/tree/test_txtcntr.html
+++ /dev/null
@@ -1,102 +0,0 @@
-<!DOCTYPE html>
-<html>
-
-<head>
-  <title>HTML text containers tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/MochiKit/packed.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/common.js"></script>
-  <script type="application/javascript"
-          src="chrome://mochikit/content/a11y/accessible/role.js"></script>
-
-  <script type="application/javascript">
-    function doTest()
-    {
-      var accTree = {
-        role: ROLE_SECTION,
-        children: [
-          { // text child
-            role: ROLE_TEXT_LEAF,
-            children: []
-          }
-        ]
-      };
-
-      testAccessibleTree("c1", accTree);
-      testAccessibleTree("c2", accTree);
-
-      accTree = {
-        role: ROLE_SECTION,
-        children: [
-          {
-            role: ROLE_TEXT_LEAF,
-            name: "Hello1"
-          },
-          {
-            role: ROLE_WHITESPACE
-          },
-          {
-            role: ROLE_TEXT_LEAF,
-            name: "Hello2"
-          },
-          {
-            role: ROLE_SEPARATOR
-          },
-          {
-            role: ROLE_TEXT_LEAF,
-            name: "Hello3 "
-          },
-          {
-            role: ROLE_PARAGRAPH,
-            children: [
-              {
-                role: ROLE_TEXT_LEAF,
-                name: "Hello4 "
-              }
-            ]
-          }
-        ]
-      };
-
-      testAccessibleTree("c3", accTree);
-
-      SimpleTest.finish();
-    }
-
-    SimpleTest.waitForExplicitFinish();
-    addA11yLoadEvent(doTest);
-  </script>
-</head>
-<body>
-
-  <a target="_blank"
-     title="overflowed content doesn't expose child text accessibles"
-     href="https://bugzilla.mozilla.org/show_bug.cgi?id=489306">Mozilla Bug 489306</a>
-  <p id="display"></p>
-  <div id="content" style="display: none"></div>
-  <pre id="test">
-  </pre>
-
-  <div id="c1" style="width: 100px; height: 100px; overflow: auto;">
-    1hellohello 2hellohello 3hellohello 4hellohello 5hellohello 6hellohello 7hellohello
-  </div>
-  <div id="c2">
-    1hellohello 2hellohello 3hellohello 4hellohello 5hellohello 6hellohello 7hellohello
-  </div>
-  <div id="c3">
-    Hello1<br>
-    Hello2<hr>
-    Hello3
-    <p>
-      Hello4
-    </p>
-  </div>
-</body>
-</html>
diff --git a/accessible/tests/mochitest/tree/test_txtctrl.html b/accessible/tests/mochitest/tree/test_txtctrl.html
index c6e40360a794..17878069c966 100644
--- a/accessible/tests/mochitest/tree/test_txtctrl.html
+++ b/accessible/tests/mochitest/tree/test_txtctrl.html
@@ -2,9 +2,8 @@
 <html>
 
 <head>
-  <title>HTML text controls tests</title>
-  <link rel="stylesheet" type="text/css"
-        href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+  <title>HTML text containers tests</title>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
 
   <script type="application/javascript"
           src="chrome://mochikit/content/MochiKit/packed.js"></script>
@@ -19,58 +18,17 @@
   <script type="application/javascript">
     function doTest()
     {
-      // editable div
       var accTree = {
         role: ROLE_SECTION,
         children: [
           { // text child
-            role: ROLE_TEXT_LEAF,
-            children: []
+            role: ROLE_TEXT_LEAF
           }
         ]
       };
 
-      testAccessibleTree("txc1", accTree);
-
-      // input@type="text"
-      accTree = {
-        role: ROLE_ENTRY,
-        children: [
-          { // text child
-            role: ROLE_TEXT_LEAF,
-            children: []
-          }
-        ]
-      };
-
-      testAccessibleTree("txc2", accTree);
-
-      // textarea
-      accTree = {
-        role: ROLE_ENTRY,
-        children: [
-          {
-            role: ROLE_TEXT_LEAF // hello1 text
-          },
-          {
-            role: ROLE_WHITESPACE
-          },
-          {
-            role: ROLE_TEXT_LEAF, // hello2 text
-          },
-          {
-            role: ROLE_WHITESPACE
-          },
-          {
-            role: ROLE_TEXT_LEAF, // whitepsace text
-          },
-          {
-            role: ROLE_WHITESPACE
-          }
-        ]
-      };
-
-      testAccessibleTree("txc3", accTree);
+      testAccessibleTree("c1", accTree);
+      testAccessibleTree("c2", accTree);
 
       SimpleTest.finish();
     }
@@ -89,14 +47,11 @@
   <pre id="test">
   </pre>
 
-  <div id="txc1" contentEditable="true">
-    1hellohello
+  <div id="c1" style="width: 100px; height: 100px; overflow: auto;">
+    1hellohello 2hellohello 3hellohello 4hellohello 5hellohello 6hellohello 7hellohello
+  </div>
+  <div id="c2">
+    1hellohello 2hellohello 3hellohello 4hellohello 5hellohello 6hellohello 7hellohello
   </div>
-  <input id="txc2" value="hello">
-  <textarea id="txc3">
-    hello1
-    hello2
-  </textarea>
-
 </body>
 </html>