receiver->RemoveEventListener(NS_ConvertASCIItoUCS2("dragover"), mDragOverListener, PR_TRUE);
receiver->RemoveEventListener(NS_LITERAL_STRING("dragover"), mDragOverListener, PR_TRUE);
nsXULTreeOuterGroupFrame::~nsXULTreeOuterGroupFrame(){  NS_IF_RELEASE(mScrollSmoother);  // TODO cancel posted events.  nsCOMPtr<nsIContent> content;  GetContent(getter_AddRefs(content));  nsCOMPtr<nsIDOMEventReceiver> receiver(do_QueryInterface(content));  // NOTE: the last Remove will delete the drag capturer  if ( receiver && mDragOverListener )     receiver->RemoveEventListener(NS_ConvertASCIItoUCS2("dragover"), mDragOverListener, PR_TRUE);    delete mRowGroupInfo;#if USE_TIMER_TO_DELAY_SCROLLING  StopScrollTracking();  mAutoScrollTimer = nsnull;#endif}