add:  getCompositeCalendar().removeObserver(agendaTreeView.calendarObserver); getCompositeCalendar().removeObserver(ltnCompositeCalendarObserver); getCalendarManager().removeObserver(ltnCalendarManagerObserver); 
context: function ltnFinish() {    var prefService = Components.classes["@mozilla.org/preferences-service;1"]                            .getService(Components.interfaces.nsIPrefService);    // Remove the pref observer    var pb2 = prefService.getBranch("");    pb2 = pb2.QueryInterface(Components.interfaces.nsIPrefBranch2);    pb2.removeObserver("calendar.", ltnPrefObserver);    return;}
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/d271fb2657c9f35b24796ae2b704e83120462f68/messenger-overlay-sidebar.js/clean/calendar/lightning/content/messenger-overlay-sidebar.js