rem: try { getWebNavigation().gotoIndex(index); } catch(ex) { return false; 
add:  if (index == "back") gBrowser.goBackGroup(); else if (index ==  "forward") gBrowser.goForwardGroup(); else { try { getWebNavigation().gotoIndex(index); } catch(ex) { return false; } 
context: function gotoHistoryIndex(aEvent){  var index = aEvent.target.getAttribute("index");  if (!index)    return false;  try {    getWebNavigation().gotoIndex(index);  }  catch(ex) {    return false;  }  return true;}
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/756d8ef90771facfd65741edf43cb5d293e97d8d/navigator.js/clean/xpfe/browser/resources/content/navigator.js