Resize Custom Server Control

[FancyPrairie]

I don't know how to setup a custom server control so that when I drop the control in the design window of Visual Studio 2005, I'll be able to resize it simply by grabbing the resize handles of the control.

What am I misssing?

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Text
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.Design
Imports System.Web.UI.Design.WebControls


<DefaultProperty("Text"), ToolboxData("<{0}:SingleTextBox runat=server></{0}:SingleTextBox>")> _
Public Class SingleTextBox
    Inherits System.Web.UI.WebControls.WebControl
    Implements INamingContainer

    Dim tbFirst As TextBox

    <Bindable(True), Category("Appearance"), DefaultValue(""), Themeable(False), Localizable(True)> _
    Property Text() As String
        Get
            Dim s As String = CStr(ViewState("Text"))
            If s Is Nothing Then
                Return String.Empty
            Else
                Return s
            End If
        End Get

        Set(ByVal Value As String)
            ViewState("Text") = Value
        End Set
    End Property

    Protected Overrides Sub CreateChildCOntrols()
        tbFirst = New TextBox
        Controls.Add(tbFirst)
    End Sub

    Protected Overrides Sub render(ByVal output As HtmlTextWriter)
        EnsureChildControls()
        RenderChildren(output)
    End Sub

End Class