add:  var calendarList = document.getElementById("list-calendars-listbox"); calendarList.removeEventListener("select", onCalendarListSelect, true);  
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);}
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/41b40d7f8cff32f4fd05afd596e8f7e47211f1e4/calendarManagement.js/buggy/calendar/resources/content/calendarManagement.js