add:  pref.removeObserver(window.buttonPrefListener.domain, window.buttonPrefListener); window.offlineObserver.unload();  
context: function Shutdown(){  try {    // If bookmarks are dirty, flush 'em to disk    var bmks = Components.classes["@mozilla.org/browser/bookmarks-service;1"]                         .getService(Components.interfaces.nsIRDFRemoteDataSource);    bmks.Flush();  } catch (ex) {  }  try {    // give history a chance at flushing to disk also    var history = Components.classes["@mozilla.org/browser/global-history;1"]                            .getService(Components.interfaces.nsIRDFRemoteDataSource);    history.Flush();  } catch (ex) {  }  // Close the app core.  if (appCore)    appCore.close();}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/dd964b18f16afa1ddbfe9284f4efe4f7ac5f3da5/navigator.js/clean/xpfe/browser/resources/content/navigator.js