add: if( canAdvance && document.getElementById("calendar-uri").value ) canAdvance = checkURL(); 
context: function checkRequired() {    var canAdvance = true;    var curPage = document.getElementById('calendar-wizard').currentPage;    if (curPage) {        var eList = curPage.getElementsByAttribute('required', 'true');        for (var i = 0; i < eList.length && canAdvance; ++i) {            canAdvance = (eList[i].value != "");        }        document.getElementById('calendar-wizard').canAdvance = canAdvance;    }}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/8bf2e98e88b44a2e0ae8b08d7bf629023206380f/calendarCreation.js/buggy/calendar/resources/content/calendarCreation.js