rem: isValid = BookmarksUtils.isSelectionValidForInsertion(aSelection, aTarget); 
add: var isValid = BookmarksUtils.isSelectionValidForInsertion(aSelection, aTarget); 
context:   insertAndCheckSelection: function (aAction, aSelection, aTarget, aTargetIndex)  {    isValid = BookmarksUtils.isSelectionValidForInsertion(aSelection, aTarget);    if (!isValid) {      SOUND.beep();      return false;    }    this.insertSelection(aAction, aSelection, aTarget, aTargetIndex);    BookmarksUtils.flushDataSource();    return true;  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/900ef0d8e7d661ae4a2ed940f8d2472235dfacd5/bookmarks.js/buggy/browser/components/bookmarks/content/bookmarks.js