@Override
 public void dispose() {
   synchronized (lock) {
     isDisposed = true;
     ToolTipManager.sharedInstance().unregisterComponent(myTree);
     myModelTracker.removeListener(this);
     myUpdateAlarm.cancelAllRequests();
     if (myUsagePreviewPanel != null) {
       UsageViewSettings.getInstance().PREVIEW_USAGES_SPLITTER_PROPORTIONS =
           ((Splitter) myUsagePreviewPanel.getParent()).getProportion();
       myUsagePreviewPanel = null;
     }
   }
 }