rem: if (!frame || !("contentWindow" in frame)) 
add: var window = getContentWindow(frame); if (!window) 
context: function checkScroll(frame){    if (!frame || !("contentWindow" in frame))        return false;    var w = frame.contentWindow;    return ((w.document.height - (w.innerHeight + w.pageYOffset)) < 160);}
meta: 1567	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/1567/ec1f57a2df47ea77b6ce245c6e2bd99b25d52195/static.js/clean/xul/content/static.js