your "base window" (Window x:Class) is some part that holds your application.
Imagine it as something like the glue between your WPF things and the underlying OS.
So just leave it what it is.
Place the RadPanelBar in this window and also the RadWindows you need.
In the handler of your RadPanelBar call the Show - or the BringToFront methods of your windows.
And a last thing - in the documentation http://www.telerik.com/help/wpf/radwindow-showing-and-positioning.html
you can read:
>>By default RadWindow
is not visible in the current page. That is why, there are numerous properties that allow By default RadWindow
is not visible in the current page. That is why, there are numerous properties that allow
This means you must (for an example in the loaded event of your applications window) call Show on the RadWindow you like to acts as "initial screen".
I hope I could give you some ideas how to start.
PS: if my answer was helpful - pleas use "Mark as answer"