rem: xulElement.setAttribute("observes", "cmd_" + aCommandName.substring(NC_NS_CMD.length)); var node = xulElement.getAttribute('observes'); 
add: xulElement.setAttribute("command", "cmd_" + aCommandName.substring(NC_NS_CMD.length)); 
context:   createMenuItem: function (aDisplayName, aCommandName, aItemNode)  {    const kXULNS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";    var xulElement = document.createElementNS(kXULNS, "menuitem");    xulElement.setAttribute("cmd", aCommandName);    xulElement.setAttribute("observes", "cmd_" + aCommandName.substring(NC_NS_CMD.length));    var node = xulElement.getAttribute('observes');    switch (aCommandName) {    case NC_NS_CMD + "open":      xulElement.setAttribute("label", aDisplayName);      xulElement.setAttribute("default", "true");      break;    case NC_NS_CMD + "openfolder":      aDisplayName = aItemNode.getAttribute("open") == "true" ? this.getLocaleString("cmd_openfolder2") : aDisplayName;      xulElement.setAttribute("label", aDisplayName);      xulElement.setAttribute("default", "true");      break;    case NC_NS_CMD + "renamebookmark":      if (!document.popupNode.hasAttribute("type")) {        xulElement.setAttribute("label", this.getLocaleString("cmd_renamebookmark2"));        xulElement.setAttribute("cmd", (NC_NS_CMD + "editurl"));      }      else        xulElement.setAttribute("label", aDisplayName);      break;    default:      xulElement.setAttribute("label", aDisplayName);      break;    }    return xulElement;  },
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/3c1e4cee57d48dad81a4af4b045f5845fa04b0f0/bookmarksTree.js/clean/xpfe/components/bookmarks/resources/bookmarksTree.js