Nested Collection Properties

Hej, jeg har et irriterende problem med Collection Properties.
I mit tilfælde har jeg brug for at have en collection property i "hovedklassen" og i hver af objekterne skal der være endnu en collection property.

Dvs en BanditItemCollection i WebControlen der består af MyThingy-objekter.
I MyThingy-objektet har jeg så MyNanoCollection der består af MyNano-objekter.

Starter med sådan set at virke fint, med output i aspx'en.
f.eks.
<cc4:WebCustomControl1 ID="WebCustomControl1_1" runat="server" BanditItemCollection-Capacity="4">
<MyThingy title="abc" amount="123" tjuhej="">
<MyNanoCollection>
<MyNano id="1" name="a" someothervalue="b" />
<MyNano id="2" name="c" someothervalue="d" />
</MyNanoCollection>
</MyThingy>
<MyThingy title="def" amount="456" tjuhej="">
<MyNanoCollection>
</MyNanoCollection>
</MyThingy>
</cc4:WebCustomControl1>

Nå men, ved skift tilbage til designtime får jeg en fejl på kontrollen..
"WebControlLibrary1.MyNanoCollection must have items of type 'WebControlLibrary1.MyNano'. 'MyNano' is of type 'System.Web.UI.HtmlControls.HtmlGenericControl'.

Nogle gode ideer?

-----------------------

    [DefaultProperty("Text")
    ,ToolboxData("<{0}:WebCustomControl1 runat=server></{0}:WebCustomControl1>")
    ,ParseChildren(false)
    ,PersistChildren(false)
    ,Designer(typeof(HtmlDesigner))
    ,ControlBuilder(typeof(HtmlBuilder))]
    public class WebCustomControl1 : System.Web.UI.WebControls.WebControl
    {
        protected MyItemCollection _myItemCollection=null;

        [
        Bindable(true)
        ,Category("Appearance")
        ,Browsable(true)
        ,PersistenceMode(PersistenceMode.InnerDefaultProperty)
        ,DesignerSerializationVisibility(DesignerSerializationVisibility.Content)       
        ]
        public MyItemCollection BanditItemCollection
        {
            get
            {
                if (_myItemCollection == null)
                    _myItemCollection = new MyItemCollection();

                return _myItemCollection;
            }
            set
            {
                _myItemCollection = value;
            }
        }

        protected override void Render(HtmlTextWriter output)
        {
            output.Write("Ostehat");
        }

        protected override void AddParsedSubObject(object obj)
        {
            if (obj is MyThingy)
            {
                MyThingy h = obj as MyThingy;

                this.BanditItemCollection.Add(new MyThingy(h.Amount, h.Title, h.Tjuhej));
            }
            else
            {
                base.AddParsedSubObject(obj);
            }
        }
    }

-----------------------------------------------

    public class MyNano
    {
        private int id;
        private string name;
        private string someothervalue;

        public int ID
        {
            get { return this.id; }
            set { this.id = value; }
        }

        public string Name
        {
            get { return this.name; }
            set { this.name = value; }
        }

        public string SomeOthervalue
        {
            get { return this.someothervalue; }
            set { this.someothervalue = value; }
        }

        public MyNano()
        {
        }

        public MyNano(int id,string name,string someothervalue)
        {
            this.id = id;
            this.name = name;
            this.someothervalue = someothervalue;
        }
    }
   
    [ParseChildren(false)
    ,PersistChildren(false)
    ,Designer(typeof(HtmlDesigner))
    ,ControlBuilder(typeof(HtmlBuilder))]
    public class MyThingy
    {
        private string sTitle;
        private int iAmount=0;
        private string sTjuhej = "";

        public string Tjuhej
        {
            get { return sTjuhej; }
            set { sTjuhej = value; }
        }

        public string Title
        {
            get { return sTitle; }
            set { sTitle = value; }
        }

        public int Amount
        {
            get {return iAmount;}
            set {iAmount=value;}
        }

        protected MyNanoCollection _myNanoCollection = null;

        [
            Bindable(true)
            , Category("Appearance")
            , Browsable(true)
            , PersistenceMode(PersistenceMode.InnerDefaultProperty)
            , DesignerSerializationVisibility(DesignerSerializationVisibility.Content)
            , Description("Returns the collection of colors to list as options when"
                + " the Palette property is set to UserDefined")
        ]
        public MyNanoCollection MyNanoCollection
        {
            get
            {
                if (_myNanoCollection == null)
                    _myNanoCollection = new MyNanoCollection();

                return _myNanoCollection;
            }
            set
            {
                _myNanoCollection = value;
            }
        }

        public MyThingy()
        {
           
        }

        public MyThingy(int aAmount,string aTitle,string aTjuhej)
        {
            iAmount = aAmount;
            sTitle = aTitle;

        }
    }

    public class MyNanoCollection : CollectionBase
    {
        public int Add(MyNano aItem)
        {
            return List.Add(aItem);
        }

        public void Insert(int aIndex, MyNano aItem)
        {
            List.Insert(aIndex, aItem);
        }

        public void Remove(MyNano aItem)
        {
            List.Remove(aItem);
        }

        public bool Contains(MyNano aItem)
        {
            return List.Contains(aItem);
        }

        public int IndexOf(MyNano aItem)
        {
            return List.IndexOf(aItem);
        }

        public void CopyTo(MyNano[] aArray, int aIndex)
        {
            List.CopyTo(aArray, aIndex);
        }

        public MyNano this[int aIndex]
        {
            get { return (MyNano)List[aIndex]; }
            set { List[aIndex] = value; }
        }
    }

    public class MyItemCollection : CollectionBase
    {
        public int Add(MyThingy aItem)
        {
            return List.Add(aItem);
        }

        public void Insert(int aIndex, MyThingy aItem)
        {
            List.Insert(aIndex, aItem);
        }

        public void Remove(MyThingy aItem)
        {
            List.Remove(aItem);
        }

        public bool Contains(MyThingy aItem)
        {
            return List.Contains(aItem);
        }

        public int IndexOf(MyThingy aItem)
        {
            return List.IndexOf(aItem);
        }

        public void CopyTo(MyThingy[] aArray, int aIndex)
        {
            List.CopyTo(aArray, aIndex);
        }

        public MyThingy this[int aIndex]
        {
            get { return (MyThingy)List[aIndex]; }
            set { List[aIndex] = value; }
        }
    }

-----------------------------------------------------

    public class HtmlDesigner : ControlDesigner
    {       
        public override string GetPersistInnerHtml()
        {
            StringWriter sw = new StringWriter();
            HtmlTextWriter html = new HtmlTextWriter(sw);

            WebCustomControl1 dd = this.Component as WebCustomControl1;
            if (dd!=null)
            {
                foreach (MyThingy c in dd.BanditItemCollection)
                {
                    html.WriteBeginTag("MyThingy");
                    html.WriteAttribute("title",c.Title);
                    html.WriteAttribute("amount", c.Amount.ToString());
                    html.WriteAttribute("tjuhej", c.Tjuhej);
                    html.WriteLine(HtmlTextWriter.TagRightChar);

                    html.WriteBeginTag("MyNanoCollection");
                    html.WriteLine(HtmlTextWriter.TagRightChar);/**/
                    foreach (MyNano nano in c.MyNanoCollection)
                    {
                        html.WriteBeginTag("MyNano");
                        html.WriteAttribute("id", nano.ID.ToString());
                        html.WriteAttribute("name", nano.Name);
                        html.WriteAttribute("someothervalue", nano.SomeOthervalue);
                        html.WriteLine(HtmlTextWriter.SelfClosingTagEnd);
                    }
                    html.WriteEndTag("MyNanoCollection");

                    html.WriteEndTag("MyThingy");
                }
            }
            return sw.ToString();/**/
            //return "GetPersistInnerHtml";
        }
    }

--------------------------------------------------------

    public class HtmlBuilder : ControlBuilder
    {
        public override Type GetChildControlType(string tagName, IDictionary attribs)
        {
            if (string.Compare(tagName, "MyThingy", true) == 0)
                return typeof(MyThingy);

            if (string.Compare(tagName, "MyNano", true) == 0)
                return typeof(MyNano);

            if (string.Compare(tagName, "MyNanoCollection", true) == 0)
                return typeof(MyNanoCollection);
         
            return base.GetChildControlType(tagName, attribs);
        }
    }