屏蔽alt+f4代码，一个变通的方法

<script language="javascript"> function document.onkeydown() { if ((window.event.altKey)&&(window.event.keyCode==115)) { window.showModelessDialog("about:blank","","dialogWidth:0px;dialogheight:0px"); return false; } } </script>
[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]