实现DataGrid标题不移出的效果

private void dgr_ItemCreated(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
  {
   if(e.Item.ItemType == ListItemType.Header)
   {
    e.Item.Style.Add("position","relative;top:expression(document.all['dgr'].offsetParent.scrollTop);");
   }
  }