WPF Popup as Model Window

Hi,

I want to develop WPF application that contains

1- Buttons on Left/Bottom/Right edge of the window.

2- Center part contains 3 sections, which are default usercontrols.

3- Now When I click on any button from edge of the windows, it will open one popup that is model to window means i can not access any parent controls. 

I am not able to get any idea how to open usercontrol in popup using MVVM pattern(make sure i dont want to temper MVVM)

Thanks,

Rajnikant