Fix for bug 6459.

layout/xul/base/src/nsTreeCellFrame.cpp

@@ -318,7 +318,8 @@ void nsTreeCellFrame::Hover(nsIPresContext& aPresContext, PRBool isHover, PRBool
   NS_IF_RELEASE(pParentContent);
 }
 
-// XXX This method will go away.
+// XXX This method will go away.  I think it can
+// actually go away now... ?
 NS_IMETHODIMP
 nsTreeCellFrame::AttributeChanged(nsIPresContext* aPresContext,
                                   nsIContent* aChild,
@@ -333,3 +334,10 @@ nsTreeCellFrame::AttributeChanged(nsIPresContext* aPresContext,
 
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsTreeCellFrame::DeleteFrame(nsIPresContext& aPresContext)
+{
+  mTreeFrame->RemoveFromSelection(this);
+  return nsTableCellFrame::DeleteFrame(aPresContext);
+}

layout/xul/base/src/nsTreeCellFrame.h

@@ -44,6 +44,8 @@ public:
                     const nsHTMLReflowState& aReflowState,
                     nsReflowStatus& aStatus);
 
+  NS_IMETHOD DeleteFrame(nsIPresContext& aPresContext);
+
   NS_IMETHOD
   AttributeChanged(nsIPresContext* aPresContext,
                                   nsIContent* aChild,

layout/xul/base/src/nsTreeFrame.cpp

@@ -160,6 +160,21 @@ void nsTreeFrame::ClearSelection(nsIPresContext& aPresContext)
 	mSelectedItems.Clear();
 }
 
+void
+nsTreeFrame::RemoveFromSelection(nsTreeCellFrame* frame)
+{
+  PRInt32 count = mSelectedItems.Count();
+  for (PRInt32 i = 0; i < count; i++)
+	{
+		// Remove the tree cell from the selection.
+		nsTreeCellFrame* theFrame = (nsTreeCellFrame*)mSelectedItems[i];
+    if (theFrame == frame) {
+      mSelectedItems.RemoveElementAt(i);
+      break;
+    }
+	}
+}
+
 void nsTreeFrame::MoveUp(nsIPresContext& aPresContext, nsTreeCellFrame* pFrame)
 {
 	PRInt32 rowIndex;

layout/xul/base/src/nsTreeFrame.h

@@ -31,6 +31,7 @@ public:
   void ClearSelection(nsIPresContext& presContext);
   void ToggleSelection(nsIPresContext& presContext, nsTreeCellFrame* pFrame);
   void RangedSelection(nsIPresContext& aPresContext, nsTreeCellFrame* pEndFrame);
+  void RemoveFromSelection(nsTreeCellFrame* frame);
 
   void MoveUp(nsIPresContext& aPresContext, nsTreeCellFrame* pFrame);
   void MoveDown(nsIPresContext& aPresContext, nsTreeCellFrame* pFrame);
@@ -47,4 +48,4 @@ protected:
 
 protected: // Data Members
 	nsVoidArray mSelectedItems; // The selected cell frames. 
-}; // class nsTableFrame
+}; // class nsTreeFrame