add: else { properties.AppendElement(ltnGetAtom("unchecked")); } 
context:     getCellProperties: function (row, col, properties)    {        if (col.id == "col-calendar-Checkbox") {            var cal = getCalendars()[row];            if (getCompositeCalendar().getCalendar(cal.uri)) {                properties.AppendElement(ltnGetAtom("checked"));            }        }    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/bfa41771724a1a302dcd3216ff3e3da767d0da35/calendar-management.js/clean/calendar/lightning/content/calendar-management.js