rem: try { var alertService = Components.classes["@mozilla.org/alerts-service;1"].getService(Components.interfaces.nsIAlertsService); } catch(ex) { var newMailNotificationAlertUI = document.getElementById("newMailNotificationAlert"); newMailNotificationAlertUI.setAttribute("hidden","true"); } 
add: var newMailNotificationAlertUI = document.getElementById("newMailNotificationAlert"); newMailNotificationAlertUI.hidden = !("@mozilla.org/alerts-service;1" in Components.classes); 
context: function Startup(){  PlaySoundCheck();  // if we can't get the alert service, hide the pref UI for using alerts to notify on new mail  // see bug #158711  try {    var alertService = Components.classes["@mozilla.org/alerts-service;1"].getService(Components.interfaces.nsIAlertsService);  }  catch(ex) {    var newMailNotificationAlertUI = document.getElementById("newMailNotificationAlert");    newMailNotificationAlertUI.setAttribute("hidden","true");  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/a583b2467bb6ebe1ccd244e3bb81f5c131813783/pref-notifications.js/buggy/mailnews/base/prefs/resources/content/pref-notifications.js