add: if (this.readOnly) throw Components.interfaces.calIErrors.CAL_IS_READONLY; 
context:     modifyItem: function (aNewItem, aOldItem, aListener) {        this.queue.push({action:'modify', oldItem: aOldItem,                         newItem: aNewItem, listener:aListener});        this.processQueue();    },
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/8127ab2430d6b0c7879a491f0176f55c41966c25/calICSCalendar.js/buggy/calendar/providers/ics/calICSCalendar.js