rem: return false; 
add:  if (aMenuItem.hasAttribute("selection")) { var showRules = aMenuItem.getAttribute("selection").split("|"); var anyMatched = false; function metaDataNodeMatches(metaDataNode, rules) { for (var i=0; i < rules.length; i++) { if (rules[i] in metaDataNode) return true; }  return false; } for (var i = 0; i < aMetaData.length; ++i) { if (metaDataNodeMatches(aMetaData[i], showRules)) anyMatched = true; else return false; } return anyMatched; }  return !aMenuItem.hidden; 
context:   _shouldShowMenuItem: function(metadata, rules) {    for (var i = 0; i < rules.length; ++i) {      if (rules[i] in metadata)        return true;    }    return false;  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10234/dae01d62ef39570e32161afc62866f13056e324e/controller.js/clean/browser/components/places/content/controller.js