rem: var xulElement = document.createElementNS(XUL_NS, "menuitem"); 
add: var xulElement = document.createElementNS(gXUL_NS, "menuitem"); 
context:   createMenuItem: function (aDisplayName, aAccessKey, aCommandName, aSelection)  {    var xulElement = document.createElementNS(XUL_NS, "menuitem");    xulElement.setAttribute("cmd", aCommandName);    var cmd = "cmd_" + aCommandName.substring(NC_NS_CMD.length);    xulElement.setAttribute("command", cmd);        if (aCommandName == NC_NS_CMD + "bm_expandfolder") {      var shouldCollapse = true;      for (var i=0; i<aSelection.length; ++i)        if (!aSelection.isExpanded[i])          shouldCollapse = false;      if (shouldCollapse) {        aDisplayName = BookmarksUtils.getLocaleString("cmd_bm_collapsefolder");        aAccessKey   = BookmarksUtils.getLocaleString("cmd_bm_collapsefolder_accesskey");      }    }    xulElement.setAttribute("label", aDisplayName);    xulElement.setAttribute("accesskey", aAccessKey);    return xulElement;  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/da13e64cf2f4fd9692155e90cae7223431174c1d/bookmarks.js/clean/browser/components/bookmarks/content/bookmarks.js