Thank you, that did what I expected.  There is one thing I don't understand though.  If I add controls dynamically this way, you can not also add additional controls via the design surface.

 Here is an example of what I am talking about.  I inerit from the webdialogwindow and add some buttons.  Another developer can then drop this new control on the design surface and start adding controls to the markup. The problem is that none of the new controls show up.  If I skip over adding the buttons, then the additional controls will show up. 

So I can only seem to get one or the other.  Is there a way to allow developers to use the new control on the design surface and still add controls dynamically?

 Thanks again for you help.

-Daniel

Daniel,

Looks like you're adding the control to the wrong controls collection.  You'll want to use the ConentPane.Controls collection instead.  That's why your control isn't showing up in the content area of the Dialog Window.  Also, here's a quick tip for extending one of our controls in this type of scenario- use the CreateChildControls override.  I'm not sure if this was what you were already doing, but it's the recommended approach.  Here's a quick example:

public class MyDialog : WebDialogWindow
{
    protected override void CreateChildControls()
    {
        base.CreateChildControls();
        TextBox tb = new TextBox();
        tb.ID = "tb1";
        tb.Text = "text";
        this.ContentPane.Controls.Add(tb);
    }
}

Thanks for the response.

The problem is I want to inherit from the Dialog control and add my standard controls to the inherited class.  Is this something that can be done with the dialog control?  If not then I will just end up creating my own .ascx control which contains the dialog, but I was hoping to inherit from it instead.

-Daniel