rem: var emptyElement = document.createElementNS(XUL_NS, "menuitem"); 
add: var emptyElement = document.createElementNS(gXUL_NS, "menuitem"); 
context:   showEmptyItem: function (aTarget)  {    if(aTarget.hasChildNodes())      return;    var EmptyMsg = BookmarksUtils.getLocaleString("emptyFolder");    var emptyElement = document.createElementNS(XUL_NS, "menuitem");    emptyElement.setAttribute("id", "empty-menuitem");    emptyElement.setAttribute("label", EmptyMsg);    emptyElement.setAttribute("disabled", "true");    aTarget.appendChild(emptyElement);  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/5d726a8d7b8ffd957682f360f58e73a7d277d96b/bookmarksMenu.js/clean/browser/components/bookmarks/content/bookmarksMenu.js