生成控件错误.请帮忙看看
//ToolBar.cs
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Lib.UI
{
[ToolboxData( " <{0}:ToolBar runat=server> </{0}:ToolBar> ")]
[ParseChildren(true, "ButtonCollection ")]
public class ToolBar : WebControl
{
private　List <ToolBarButton> 　buttonCollection;

[
Category( "集合 "),
Description( "项集合 "),
DesignerSerializationVisibility(
DesignerSerializationVisibility.Content),
PersistenceMode(PersistenceMode.InnerDefaultProperty)

]

public List <ToolBarButton> ButtonCollection
{
get
{
if (buttonCollection == null)
buttonCollection = new List <ToolBarButton> ();
return buttonCollection;
}
set
{
buttonCollection = value;
}

}
protected override void CreateChildControls()
{
this.EnsureChildControls();
base.CreateChildControls();
}

protected override void Render(HtmlTextWriter writer)
{

writer.AddStyleAttribute(HtmlTextWriterStyle.Width, "100% ");
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderColor, "#ffccee ");
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderStyle, BorderStyle.Groove.ToString());
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderWidth, "1px ");
writer.AddStyleAttribute(HtmlTextWriterStyle.TextAlign, TextAlign.Right.ToString());
writer.RenderBeginTag(HtmlTextWriterTag.Div);
foreach (ToolBarButton bt in buttonCollection)
{
bt.RenderControl(writer);
}
writer.RenderEndTag();
}

}
}
//ToolBarButton.cs
using System;
using System.ComponentModel;
using System.Web.UI;
namespace Lib.UI
{
/// <summary>
/// ToolBar按钮
/// </summary>
///
public class ToolBarButton:Control,IPostBackEventHandler

{
private string _text;
private string _commandname;
private string _clientscript;

// 声明Click事件委托
private static readonly object ClickKey = new object();



[Description( "显示文本 ")]
[NotifyParentProperty(true)]
[Category( "按钮集合 ")]
public string Text
{
get { return _text; }
set { _text = value; }
}

[Description( "按钮名称 ")]
[NotifyParentProperty(true)]
[Category( "按钮集合 ")]
public string CommandName
{
get { return _commandname; }
set { _commandname = value; }
}

[Description( "客户端脚本对象 ")]
[NotifyParentProperty(true)]
[Category( "按钮集合 ")]
public string ClientScript
{
get { return _clientscript; }
set { _clientscript = value; }
}
public event EventHandler Click
{
add
{
Events.AddHandler(ClickKey, value);
}
remove
{
Events.RemoveHandler(ClickKey, value);
}
}

// 定义OnClick事件处理程序
protected virtual void OnClick(EventArgs e)
{
EventHandler clickEventDelegate =
(EventHandler)Events[ClickKey];
if (clickEventDelegate != null)
{
clickEventDelegate(this, e);

}
}

// 实现RaisePostBackEvent方法,处理回发事件
public void RaisePostBackEvent(string eventArgument)
{
OnClick(EventArgs.Empty);
}

protected override void Render(HtmlTextWriter writer)
{
writer.AddStyleAttribute( "CommandName ", this._commandname);
writer.AddAttribute( "onclick ", Page.ClientScript.GetPostBackClientHyperlink(this, this._commandname));
//这里Page对象是null的,为何这样?
writer.AddStyleAttribute(HtmlTextWriterStyle.Cursor, "hand ");
writer.AddAttribute(HtmlTextWriterAttribute.Title, this._text);
writer.RenderBeginTag(HtmlTextWriterTag.Div);
writer.Write(this._text);
writer.RenderEndTag();
}

}
}


[解决办法]
当前控件并没有添加到页面中，当成了普通的类来运行。
[解决办法]
可以改成： Page p = (Page)System.Web.HttpContext.Current.Handler; writer.AddAttribute( "onclick ", p.ClientScript.GetPostBackClientHyperlink(this, this._commandname));