diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 4cf5cb5460c..0cef3e36547 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -3348,6 +3348,35 @@ nsFrame::AttributeChanged(PRInt32         aNameSpaceID,
   return NS_OK;
 }
 
+PRBool nsFrame::GetMouseThrough() const
+{
+  eMouseThrough mousethrough = unset;
+
+  if (mContent) {
+    static nsIContent::AttrValuesArray strings[] =
+      {&nsGkAtoms::never, &nsGkAtoms::always, nsnull};
+    static const eMouseThrough values[] = {never, always};
+    PRInt32 index = mContent->FindAttrValueIn(kNameSpaceID_None,
+        nsGkAtoms::mousethrough, strings, eCaseMatters);
+    if (index >= 0) {
+      mousethrough = values[index];
+    }
+  }
+
+  switch(mousethrough)
+  {
+    case always:
+      return PR_TRUE;
+    case never:
+      return PR_FALSE;
+    case unset:
+      if (mParent)
+        return mParent->GetMouseThrough();
+  }
+
+  return PR_FALSE;
+}
+
 // Flow member functions
 
 nsSplittableType
diff --git a/layout/generic/nsFrame.h b/layout/generic/nsFrame.h
index 28b7a8bd69b..7404cb0aecb 100644
--- a/layout/generic/nsFrame.h
+++ b/layout/generic/nsFrame.h
@@ -206,6 +206,8 @@ public:
                                         PRInt8 aOutSideLimit
                                         );
 
+  PRBool GetMouseThrough() const;
+
   /**
    * Find the nearest frame with a mouse capturer. If no
    * parent has mouse capture this will return null.
diff --git a/layout/xul/base/src/nsBoxFrame.cpp b/layout/xul/base/src/nsBoxFrame.cpp
index 9454879894e..3586082619d 100644
--- a/layout/xul/base/src/nsBoxFrame.cpp
+++ b/layout/xul/base/src/nsBoxFrame.cpp
@@ -136,8 +136,7 @@ nsBoxFrame::nsBoxFrame(nsIPresShell* aPresShell,
                        nsStyleContext* aContext,
                        PRBool aIsRoot,
                        nsIBoxLayout* aLayoutManager) :
-  nsContainerFrame(aContext),
-  mMouseThrough(unset)
+  nsContainerFrame(aContext)
 {
   mState |= NS_FRAME_IS_BOX;
   mState |= NS_STATE_IS_HORIZONTAL;
@@ -222,47 +221,12 @@ nsBoxFrame::Init(nsIContent*      aContent,
       GetDebugPref(GetPresContext());
 #endif
 
-  mMouseThrough = unset;
-
-  UpdateMouseThrough();
-
   // register access key
   rv = RegUnregAccessKey(PR_TRUE);
 
   return rv;
 }
 
-void nsBoxFrame::UpdateMouseThrough()
-{
-  if (mContent) {
-    static nsIContent::AttrValuesArray strings[] =
-      {&nsGkAtoms::never, &nsGkAtoms::always, nsnull};
-    static const eMouseThrough values[] = {never, always};
-    PRInt32 index = mContent->FindAttrValueIn(kNameSpaceID_None,
-        nsGkAtoms::mousethrough, strings, eCaseMatters);
-    if (index >= 0) {
-      mMouseThrough = values[index];
-    }
-  }
-}
-
-PRBool
-nsBoxFrame::GetMouseThrough() const
-{
-  switch(mMouseThrough)
-  {
-    case always:
-      return PR_TRUE;
-    case never:
-      return PR_FALSE;
-    case unset:
-      if (mParent && mParent->IsBoxFrame())
-        return mParent->GetMouseThrough();
-  }
-
-  return PR_FALSE;
-}
-
 void
 nsBoxFrame::CacheAttributes()
 {
@@ -1141,7 +1105,6 @@ nsBoxFrame::AttributeChanged(PRInt32 aNameSpaceID,
       aAttribute == nsGkAtoms::orient       ||
       aAttribute == nsGkAtoms::pack         ||
       aAttribute == nsGkAtoms::dir          ||
-      aAttribute == nsGkAtoms::mousethrough ||
       aAttribute == nsGkAtoms::equalsize) {
 
     if (aAttribute == nsGkAtoms::align  ||
@@ -1206,9 +1169,6 @@ nsBoxFrame::AttributeChanged(PRInt32 aNameSpaceID,
              aAttribute == nsGkAtoms::top) {
       mState &= ~NS_STATE_STACK_NOT_POSITIONED;
     }
-    else if (aAttribute == nsGkAtoms::mousethrough) {
-      UpdateMouseThrough();
-    }
 
     PresContext()->PresShell()->
       FrameNeedsReflow(this, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
diff --git a/layout/xul/base/src/nsBoxFrame.h b/layout/xul/base/src/nsBoxFrame.h
index 245dc93d30b..5f0a73bb1f7 100644
--- a/layout/xul/base/src/nsBoxFrame.h
+++ b/layout/xul/base/src/nsBoxFrame.h
@@ -112,7 +112,6 @@ public:
   virtual Halignment GetHAlign() const { return mHalign; }
   NS_IMETHOD DoLayout(nsBoxLayoutState& aBoxLayoutState);
 
-  virtual PRBool GetMouseThrough() const;
   virtual PRBool ComputesOwnOverflowArea() { return PR_FALSE; }
 
   // ----- child and sibling operations ---
@@ -282,7 +281,6 @@ private:
     void DrawLine(nsIRenderingContext& aRenderingContext,  PRBool aHorizontal, nscoord x1, nscoord y1, nscoord x2, nscoord y2);
     void FillRect(nsIRenderingContext& aRenderingContext,  PRBool aHorizontal, nscoord x, nscoord y, nscoord width, nscoord height);
 #endif
-    void UpdateMouseThrough();
 
     void CacheAttributes();
 
@@ -292,8 +290,6 @@ private:
     Halignment mHalign;
     Valignment mValign;
 
-    eMouseThrough mMouseThrough;
-
 #ifdef DEBUG_LAYOUT
     static PRBool gDebug;
     static nsIBox* mDebugChild;
diff --git a/layout/xul/base/src/nsLeafBoxFrame.cpp b/layout/xul/base/src/nsLeafBoxFrame.cpp
index 322c76b28a0..4e5c704bc9c 100644
--- a/layout/xul/base/src/nsLeafBoxFrame.cpp
+++ b/layout/xul/base/src/nsLeafBoxFrame.cpp
@@ -73,7 +73,7 @@ NS_NewLeafBoxFrame (nsIPresShell* aPresShell, nsStyleContext* aContext)
 } // NS_NewLeafBoxFrame
 
 nsLeafBoxFrame::nsLeafBoxFrame(nsIPresShell* aShell, nsStyleContext* aContext)
-    : nsLeafFrame(aContext), mMouseThrough(unset)
+    : nsLeafFrame(aContext)
 {
     mState |= NS_FRAME_IS_BOX;
 }
@@ -108,59 +108,10 @@ nsLeafBoxFrame::Init(
            view->CreateWidget(kWidgetCID);   
     }
   }
-  
-  mMouseThrough = unset;
-
-  UpdateMouseThrough();
 
   return rv;
 }
 
-NS_IMETHODIMP
-nsLeafBoxFrame::AttributeChanged(PRInt32 aNameSpaceID,
-                                 nsIAtom* aAttribute,
-                                 PRInt32 aModType)
-{
-  nsresult rv = nsLeafFrame::AttributeChanged(aNameSpaceID, aAttribute,
-                                              aModType);
-
-  if (aAttribute == nsGkAtoms::mousethrough) 
-    UpdateMouseThrough();
-
-  return rv;
-}
-
-void nsLeafBoxFrame::UpdateMouseThrough()
-{
-  if (mContent) {
-    static nsIContent::AttrValuesArray strings[] =
-      {&nsGkAtoms::never, &nsGkAtoms::always, nsnull};
-    switch (mContent->FindAttrValueIn(kNameSpaceID_None,
-                                      nsGkAtoms::mousethrough,
-                                      strings, eCaseMatters)) {
-      case 0: mMouseThrough = never; break;
-      case 1: mMouseThrough = always; break;
-    }
-  }
-}
-
-PRBool
-nsLeafBoxFrame::GetMouseThrough() const
-{
-  switch (mMouseThrough)
-  {
-    case always:
-      return PR_TRUE;
-    case never:
-      return PR_FALSE;
-    case unset:
-      if (mParent && mParent->IsBoxFrame())
-        return mParent->GetMouseThrough();
-  }
-
-  return PR_FALSE;
-}
-
 NS_IMETHODIMP
 nsLeafBoxFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                  const nsRect&           aDirtyRect,
diff --git a/layout/xul/base/src/nsLeafBoxFrame.h b/layout/xul/base/src/nsLeafBoxFrame.h
index fef1b9e4b5e..384e0a39599 100644
--- a/layout/xul/base/src/nsLeafBoxFrame.h
+++ b/layout/xul/base/src/nsLeafBoxFrame.h
@@ -94,11 +94,6 @@ public:
                               const nsRect&           aDirtyRect,
                               const nsDisplayListSet& aLists);
 
-  NS_IMETHOD AttributeChanged(PRInt32 aNameSpaceID,
-                              nsIAtom* aAttribute,
-                              PRInt32 aModType);
-
-  virtual PRBool GetMouseThrough() const;
   virtual PRBool ComputesOwnOverflowArea() { return PR_FALSE; }
 
 protected:
@@ -116,14 +111,6 @@ protected:
 
  nsLeafBoxFrame(nsIPresShell* aShell, nsStyleContext* aContext);
 
-protected:
-  eMouseThrough mMouseThrough;
-
-private:
-
- void UpdateMouseThrough();
-
-
 }; // class nsLeafBoxFrame
 
 #endif /* nsLeafBoxFrame_h___ */