add: else if (aEvent.altKey) return "properties" 
context:   getBrowserTargetFromEvent: function (aEvent)  {    // note: modifier keys are ignored in menuitems (bug 126189)    var button = aEvent.type == "command"? 0:aEvent.button;    if (button == 2)      return "";    if (aEvent.metaKey || aEvent.ctrlKey || button == 1)      if (aEvent.shiftKey)        return "window";      else        return "tab";    else      return "current";  },
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/bb3ed3ed6b331b1fe471906dd2ecce1a2077a9e6/bookmarks.js/clean/browser/components/bookmarks/content/bookmarks.js