javascript实现可以拖动的层示例(层拖动，兼容IE/FF)
临时写的：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style type="text/css">
#main div{position:absolute;width:220px;height:150px;border:1px solid #999;}
</style>
<script type="text/javascript">
var a;
document.onmouseup=function(){if(!a)return;document.all?a.releaseCapture():window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);a="";};
document.onmousemove=function (d){if(!a)return;if(!d)d=event;a.style.left=(d.clientX-b)+"px";a.style.top=(d.clientY-c)+"px";};
function $(o,e){a=o;document.all?a.setCapture():window.captureEvents(Event.MOUSEMOVE);b=e.clientX-parseInt(a.style.left);c=e.clientY-parseInt(a.style.top);}
</script>
</head>
<body>
</body>
</html>
