rem: setCalendarManagerUI(); 
add: var item = getListItem(aCalendar); if (item) { document.getElementById("list-calendars-listbox").removeChild(item); } 
context:     onCalendarUnregistering: function(aCalendar) {        setCalendarManagerUI();    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/84c321621ae4b2d4fd77ffb0bd03d594aeff0ad4/calendarManagement.js/buggy/calendar/resources/content/calendarManagement.js