rem: item.setAttribute("disabled", item.isDisabled()); 
add: if (item.isDisabled()) item.setAttribute("disabled", "true"); else item.removeAttribute("disabled"); 
context:   initPopup: function(aPopup)  {    var items = aPopup.getElementsByTagName("menuitem");    var js, fn, item;    for (var i = 0; i < items.length; i++) {      item = items[i];      fn = "isDisabled" in item ? item.isDisabled : null;      if (!fn) {        js = item.getAttribute("isDisabled");        if (js) {          fn = new Function(js);          item.isDisabled = fn;        } else {          item.isDisabled = null; // to prevent annoying "strict" warning messages        }      }       if (fn) {        item.setAttribute("disabled", item.isDisabled());      }      fn = null;    }  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/1dc8b67ef1c6d089ea6e41113322d280cba4bbbc/inspector.js/clean/extensions/inspector/resources/content/inspector.js