add: pbi.removeObserver("calendar.", calPrefObserver); 
context: function finishCalendarManager() {    // Remove the category color pref observer    var pbi = prefService.getBranch("");    pbi = pbi.QueryInterface(Components.interfaces.nsIPrefBranch2);    pbi.removeObserver("calendar.category.color.", categoryPrefObserver);    var calendarList = document.getElementById("list-calendars-listbox");    calendarList.removeEventListener("select", onCalendarListSelect, true);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/5d4643e5fc09b9c9bfe79bf368cffd153d30204b/calendarManagement.js/buggy/calendar/resources/content/calendarManagement.js