有滚动条、固定Header的ASP.Net DataGrid实现

客户要一个有滚动条的ASP.Net DataGrid控件，只好写了：
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Web.UI.Design.WebControls;
using System.Text;
using System.Drawing;

[assembly:TagPrefix("Microsoft.Gtec.Dsv", "gtecdsv")]
namespace Microsoft.Gtec.Dsv
{
///

/// Summary description for WebCustomControl1.
///

[ToolboxData("<{0}:ScrollableFixedHeaderDataGrid runat=server>")]
public class ScrollableFixedHeaderDataGrid: System.Web.UI.WebControls.DataGrid
{
protected override void Render(HtmlTextWriter output)
{
//Use this flag to determine whether the component is in design-time or runtime.
//The control will be rendered differently in IDE.
//Don't bother to use DataGridDesigner.GetDesignTimeHtml
bool designMode = ((Site != null) && (Site.DesignMode));
//Backing up the properties need to change during the render process
string tempLeft = Style["LEFT"];
string tempTop = Style["TOP"];
Unit tempTABLE-LAYOUT"];

//Render a "