弹出窗口跟随scrollbar位置
<script type="text/javascript">
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(PageLoad);
function PageLoad()
{
document.getElementById('<%=popUpMsg.ClientID %>').style.top=document.documentElement.scrollTop + 100 ;
}
window.onload=PageLoad;
</script>
<div ID="popUpMsg" runat="server" Width="420px" Height="420px" Left="25%">
......