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: 1622	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/1622/3df45f52a2f3a304b5c3c14817a3c2c3cbfc6921/static.js/buggy/xul/content/static.js