Vista - WPF Child Window Question

From a WPF Newbie --

I have an application main window and I want to have a visual container of
some sort that will contain a collection of child windows. And when certain
events happen, one of the child windows is shown and the rest hidden.
Somewhat like the tabbed widows in Visual Studio.

I've been playing with window properties and I can display a modeless window
that is owned by the application window. I can't seem to figure out how to
establish the parent/child relationship though. When I move the app window,
the child just sits motionless.

Any suggestion welcome - even google search terms!

TIA,

Mike P