Make ControlLibrary User Control Hide()

I've spent three days trying to get a user control to do some obvious things -- show, hide, and focus among other things. Done in vBASIC in Visual Studio 2010 Pro. The calling program is a Windows Forms Application, while the user control is a WPF Custom Control Library with a single object, a textbox. The reason it's a user control is that this textbox is connected to an async serial device; the reason it's in a Custom Control Library is that I'd like to be able to drop this functioning serial-port-connected textbox into future projects.

No matter what syntax I attempt, the user control (neither the control nor the text box inside it) will Hide(). I've tried every variation I can think of with control.Visible = false, exposing public subs to do the work, etc. When the form appears and characters are typed in the field, the KeyPress routine is functioning -- it will only accept numeric digits.

Here's the vastly reduced code to illustrate the problem:

Calling Windows Forms Application
Imports DTRFormsControlLibrary2
Public Class Form1

[Code]...

In spite of the call to sbControl.Hide(), the form opens with a very visible and enabled user control text box. The ability to control visibility, focus, and enable/disable seems fundamental to any control.