diff --git a/accessible/src/atk/nsAppRootAccessible.cpp b/accessible/src/atk/nsAppRootAccessible.cpp
index 9d94f9bb402b..bf60b1ac99a8 100644
--- a/accessible/src/atk/nsAppRootAccessible.cpp
+++ b/accessible/src/atk/nsAppRootAccessible.cpp
@@ -678,32 +678,41 @@ NS_IMETHODIMP nsAppRootAccessible::GetChildAt(PRInt32 aChildNum,
     return rv;
 }
 
-NS_IMETHODIMP nsAppRootAccessible::GetChildCount(PRInt32 *aAccChildCount) 
+void nsAppRootAccessible::CacheChildren()
 {
-    PRUint32 count = 0;
-    nsresult rv = NS_OK;
-    if (mChildren)
-        rv = mChildren->GetLength(&count);
-    if (NS_SUCCEEDED(rv)) {
-        MAI_LOG_DEBUG(("\nGet Acc Child OK, count=%d\n", count));
+    if (!mChildren) {
+        mAccChildCount = eChildCountUninitialized;
+        return;
     }
-    else
-        MAI_LOG_DEBUG(("\nGet Acc Child Failed, count=%d\n", count));
 
-    *aAccChildCount = NS_STATIC_CAST(PRInt32, count);
-    return rv;
-}
+    if (mAccChildCount == eChildCountUninitialized) {
+        nsCOMPtr<nsISimpleEnumerator> enumerator;
+        mChildren->Enumerate(getter_AddRefs(enumerator));
 
-NS_IMETHODIMP nsAppRootAccessible::GetFirstChild(nsIAccessible * *aFirstChild) 
-{
-    nsCOMPtr<nsIAccessible> firstChild;
-    *aFirstChild = nsnull;
-    nsresult rv = NS_OK;
-    rv = mChildren->QueryElementAt(0, NS_GET_IID(nsIAccessible),
-                                   getter_AddRefs(firstChild));
-    if (firstChild)
-        NS_IF_ADDREF(*aFirstChild = firstChild);
-    return rv;
+        nsCOMPtr<nsIWeakReference> childWeakRef;
+        nsCOMPtr<nsIAccessible> accessible;
+        nsCOMPtr<nsPIAccessible> previousAccessible;
+        PRBool hasMoreElements;
+        while(NS_SUCCEEDED(enumerator->HasMoreElements(&hasMoreElements))
+              && hasMoreElements) {
+            enumerator->GetNext(getter_AddRefs(childWeakRef));
+            accessible = do_QueryReferent(childWeakRef);
+            if (accessible) {
+                if (previousAccessible) {
+                    previousAccessible->SetNextSibling(accessible);
+                }
+                else {
+                    SetFirstChild(accessible);
+                }
+                previousAccessible = do_QueryInterface(accessible);
+                previousAccessible->SetParent(this);
+            }
+        }
+
+        PRUint32 count = 0;
+        mChildren->GetLength(&count);
+        mAccChildCount = NS_STATIC_CAST(PRInt32, count);
+    }
 }
 
 NS_IMETHODIMP nsAppRootAccessible::GetNextSibling(nsIAccessible * *aNextSibling) 
@@ -746,6 +755,7 @@ nsAppRootAccessible::AddRootAccessible(nsIAccessible *aRootAccWrap)
 
     // add by weak reference
     rv = mChildren->AppendElement(aRootAccWrap, PR_TRUE);
+    InvalidateChildren();
 
     void* atkAccessible;
     aRootAccWrap->GetNativeInterface(&atkAccessible);
@@ -803,6 +813,7 @@ nsAppRootAccessible::RemoveRootAccessible(nsIAccessible *aRootAccWrap)
     rv = mChildren->RemoveElementAt(index);
 
 #endif
+    InvalidateChildren();
     return rv;
 }
 
diff --git a/accessible/src/atk/nsAppRootAccessible.h b/accessible/src/atk/nsAppRootAccessible.h
index fd593873a5b9..1034c224efe8 100644
--- a/accessible/src/atk/nsAppRootAccessible.h
+++ b/accessible/src/atk/nsAppRootAccessible.h
@@ -86,14 +86,15 @@ public:
     NS_IMETHOD GetPreviousSibling(nsIAccessible **aPreviousSibling);
     NS_IMETHOD GetChildAt(PRInt32 aChildNum, nsIAccessible **aChild);
 
-    NS_IMETHOD GetFirstChild(nsIAccessible * *aFirstChild);
-    NS_IMETHOD GetChildCount(PRInt32 *aAccChildCount);
-
     // return the atk object for app root accessible
     NS_IMETHOD GetNativeInterface(void **aOutAccessible);
 
     nsresult AddRootAccessible(nsIAccessible *aRootAccWrap);
     nsresult RemoveRootAccessible(nsIAccessible *aRootAccWrap);
+
+protected:
+    virtual void CacheChildren();
+
 private:
     nsCOMPtr<nsIMutableArray> mChildren;
 };
diff --git a/accessible/src/base/nsAccessible.cpp b/accessible/src/base/nsAccessible.cpp
index f17dac55fc06..b27876d75e0b 100644
--- a/accessible/src/base/nsAccessible.cpp
+++ b/accessible/src/base/nsAccessible.cpp
@@ -489,7 +489,7 @@ NS_IMETHODIMP nsAccessible::Shutdown()
 NS_IMETHODIMP nsAccessible::InvalidateChildren()
 {
   // Document has transformed, reset our invalid children and child count
-  mAccChildCount = -1;
+  mAccChildCount = eChildCountUninitialized;
   mFirstChild = nsnull;
   return NS_OK;
 }
@@ -667,7 +667,7 @@ void nsAccessible::CacheChildren()
 {
   if (!mWeakShell) {
     // This node has been shut down
-    mAccChildCount = -1;
+    mAccChildCount = eChildCountUninitialized;
     return;
   }
 
@@ -1968,7 +1968,7 @@ NS_IMETHODIMP nsAccessible::GetFinalState(PRUint32 *aState)
   if (!content) {
     return NS_ERROR_FAILURE;  // Node already shut down
   }
-  for (PRInt32 index = 0; index < NS_ARRAY_LENGTH(gUnivStateMap); index ++) {
+  for (PRUint32 index = 0; index < NS_ARRAY_LENGTH(gUnivStateMap); index ++) {
     MappedAttrState(content, aState, &gUnivStateMap[index]);
   }
   if (!mRoleMapEntry) {
diff --git a/accessible/src/html/nsHTMLFormControlAccessible.cpp b/accessible/src/html/nsHTMLFormControlAccessible.cpp
index 66292ded728a..47bb8bda5a8b 100644
--- a/accessible/src/html/nsHTMLFormControlAccessible.cpp
+++ b/accessible/src/html/nsHTMLFormControlAccessible.cpp
@@ -495,7 +495,7 @@ void nsHTMLGroupboxAccessible::CacheChildren()
 {
   if (!mWeakShell) {
     // This node has been shut down
-    mAccChildCount = -1;
+    mAccChildCount = eChildCountUninitialized;
     return;
   }
 
diff --git a/accessible/src/html/nsHTMLImageAccessible.cpp b/accessible/src/html/nsHTMLImageAccessible.cpp
index f357139314d4..71b54fdba9ff 100644
--- a/accessible/src/html/nsHTMLImageAccessible.cpp
+++ b/accessible/src/html/nsHTMLImageAccessible.cpp
@@ -174,7 +174,7 @@ void nsHTMLImageAccessible::CacheChildren()
 {
   if (!mWeakShell) {
     // This node has been shut down
-    mAccChildCount = -1;
+    mAccChildCount = eChildCountUninitialized;
     return;
   }
 
diff --git a/accessible/src/xul/nsXULSelectAccessible.cpp b/accessible/src/xul/nsXULSelectAccessible.cpp
index 8bd038ff3533..e1302b0613cf 100644
--- a/accessible/src/xul/nsXULSelectAccessible.cpp
+++ b/accessible/src/xul/nsXULSelectAccessible.cpp
@@ -606,7 +606,7 @@ void nsXULComboboxAccessible::CacheChildren()
 {
   if (!mWeakShell) {
     // This node has been shut down
-    mAccChildCount = -1;
+    mAccChildCount = eChildCountUninitialized;
     return;
   }