[ASP2] Problème WebControl et affichage dans le Designer

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 WebControlLibrary1
{
[DefaultProperty("Text")]
[ToolboxData("<{0}:LinkBox runat=server></{0}:LinkBox>")]
[ControlBuilder(typeof(LinkBoxControlBuilder))]
[ParseChildren(true, "Items")]
[PersistChildren(true)]
public class LinkBox : WebControl
{
//private List<LinkBoxItem> _items;
private ArrayList _items2 = new ArrayList();
public LinkBox() : base()
{
   //_items = new List<LinkBoxItem>();
   _items2 = new ArrayList();
   ViewState["Items"] = _items2;
}

//[Bindable(true)]
[Category("Appearance")]
[Localizable(false)]
[PersistenceMode(PersistenceMode.InnerDefaultProperty)]
public ArrayList Items
{
   get { return (_items2); }
   set { _items2 = value; }
}

[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Text
{
   get
   {
      String s = (String)ViewState["Text"];
      return ((s == null) ? String.Empty : s);
   }
   set { ViewState["Text"] = value; }
}

[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Title
{
   get
   {
      String s = (String)ViewState["Title"];
      return ((s == null) ? String.Empty : s);
   }
   set { ViewState["Title"] = value; }
}

protected override void AddParsedSubObject(object obj)
{
   if (obj is LinkBoxItem)
   Items.Add((LinkBoxItem)obj);
}

protected override void RenderContents(HtmlTextWriter output)
{
   ViewState["items"] = _items2;
   output.Write("<div class=\"cadretitre\">");
   output.Write("<div class=\"cadretitrepuce\">");
   output.Write("<img src=\"images/fly_small.gif\">");
   output.Write("</div>");
   output.Write("<h2> " + Title + " </h2>");
   output.Write("</div>");
   output.Write("<div class=\"cadre\">");
   output.Write("<h3> " + Text + " </h3>");
   output.Write("<p>");
   output.Write("<br />");
   foreach(LinkBoxItem itm in Items)
   {
      output.Write("<a href=\"" + itm.Url + "\" target=\"" + itm.Target + "\">" + itm.Title + "</a>");
      if (itm.Desc.Length > 0)
         output.Write(", " + itm.Desc);
      output.Write("<br />");
   }
   output.Write("</p>");
   output.Write("</div>");
}
}
}