Fix for bug 9503.

layout/base/nsCSSFrameConstructor.cpp

@@ -4601,6 +4601,22 @@ nsCSSFrameConstructor::ContentRemoved(nsIPresContext* aPresContext,
   shell->GetPrimaryFrameFor(aChild, &childFrame);
 
   if (childFrame) {
+
+#ifdef INCLUDE_XUL
+    nsCOMPtr<nsIAtom> tag;
+    aContainer->GetTag(*getter_AddRefs(tag));
+    if (tag.get() == nsXULAtoms::treechildren ||
+        tag.get() == nsXULAtoms::treeitem) {
+      // Convert to a tree row group frame.
+      nsIFrame* parentFrame;
+      childFrame->GetParent(&parentFrame);
+      nsTreeRowGroupFrame* treeRowGroup = (nsTreeRowGroupFrame*)parentFrame;
+      if (treeRowGroup && treeRowGroup->IsLazy()) {
+        treeRowGroup->OnContentRemoved(*aPresContext, childFrame);
+      }
+    }
+#endif // INCLUDE_XUL
+
     // Walk the frame subtree deleting any out-of-flow frames, and
     // remove the mapping from content objects to frames
     DeletingFrameSubtree(aPresContext, shell, childFrame, childFrame);

layout/html/style/src/nsCSSFrameConstructor.cpp

@@ -4601,6 +4601,22 @@ nsCSSFrameConstructor::ContentRemoved(nsIPresContext* aPresContext,
   shell->GetPrimaryFrameFor(aChild, &childFrame);
 
   if (childFrame) {
+
+#ifdef INCLUDE_XUL
+    nsCOMPtr<nsIAtom> tag;
+    aContainer->GetTag(*getter_AddRefs(tag));
+    if (tag.get() == nsXULAtoms::treechildren ||
+        tag.get() == nsXULAtoms::treeitem) {
+      // Convert to a tree row group frame.
+      nsIFrame* parentFrame;
+      childFrame->GetParent(&parentFrame);
+      nsTreeRowGroupFrame* treeRowGroup = (nsTreeRowGroupFrame*)parentFrame;
+      if (treeRowGroup && treeRowGroup->IsLazy()) {
+        treeRowGroup->OnContentRemoved(*aPresContext, childFrame);
+      }
+    }
+#endif // INCLUDE_XUL
+
     // Walk the frame subtree deleting any out-of-flow frames, and
     // remove the mapping from content objects to frames
     DeletingFrameSubtree(aPresContext, shell, childFrame, childFrame);

layout/xul/base/src/nsTreeFrame.cpp

@@ -55,11 +55,19 @@ nsTreeFrame::~nsTreeFrame()
 {
 }
 
-void nsTreeFrame::SetSelection(nsIPresContext& aPresContext, nsTreeCellFrame* pFrame)
+void nsTreeFrame::SetSelection(nsIPresContext& aPresContext, nsTreeCellFrame* aFrame)
 {
+  PRInt32 count = mSelectedItems.Count();
+  if (count == 1) {
+    // See if we're already selected.
+    nsTreeCellFrame* frame = (nsTreeCellFrame*)mSelectedItems[0];
+    if (frame == aFrame)
+      return;
+  }
+			
 	ClearSelection(aPresContext);
-	mSelectedItems.AppendElement(pFrame);
-	pFrame->Select(aPresContext, PR_TRUE);
+	mSelectedItems.AppendElement(aFrame);
+	aFrame->Select(aPresContext, PR_TRUE);
 
   FireChangeHandler(aPresContext);
 }

layout/xul/base/src/nsTreeRowGroupFrame.cpp

@@ -923,11 +923,17 @@ PRBool nsTreeRowGroupFrame::ContinueReflow(nsIPresContext& aPresContext, nscoord
   if (height <= 0 && IsLazy()) {
     mIsFull = PR_TRUE;
     nsIFrame* lastChild = GetLastFrame();
-    if (lastChild != mBottomFrame) {
+    nsIFrame* startingPoint = mBottomFrame;
+    if (startingPoint == nsnull) {
+      // We just want to delete everything but the first item.
+      startingPoint = GetFirstFrame();
+    }
+
+    if (lastChild != startingPoint) {
       // We have some hangers on (probably caused by shrinking the size of the window).
       // Nuke them.
       nsIFrame* currFrame;
-      mBottomFrame->GetNextSibling(&currFrame);
+      startingPoint->GetNextSibling(&currFrame);
       while (currFrame) {
         nsIFrame* nextFrame;
         currFrame->GetNextSibling(&nextFrame);
@@ -966,6 +972,14 @@ void nsTreeRowGroupFrame::OnContentAdded(nsIPresContext& aPresContext)
   }
 }
 
+void nsTreeRowGroupFrame::OnContentRemoved(nsIPresContext& aPresContext, 
+                                           nsIFrame* aChildFrame)
+{
+  // We need to make sure we update things when content gets removed.
+  // Clear out our top and bottom frames.
+  mTopFrame = mBottomFrame = nsnull;
+}
+
 void nsTreeRowGroupFrame::SetContentChain(nsISupportsArray* aContentChain)
 {
   NS_IF_RELEASE(mContentChain);

layout/xul/base/src/nsTreeRowGroupFrame.h

@@ -60,6 +60,7 @@ public:
 
   // Responses to changes
   void OnContentAdded(nsIPresContext& aPresContext);
+  void OnContentRemoved(nsIPresContext& aPresContext, nsIFrame* aChildFrame);
 
   virtual nsIFrame* GetFirstFrame();
   virtual nsIFrame* GetLastFrame();