Hi, I'm new working with Prism with WPF, and I have a question which I can't find answer. Why it is impossible to add a window in a Region ? I can understand there's a good reason, so I will need another solution to my problem. It is quite simple, I got a LoginView (Window) which I want to appear first. For the previous reason, in my Region, I added a MainView (UserControl) where I just show my LoginView on the Loaded event. The problem if the user quit the application or if he cancels his login, the MainView is still showing up. It seems a stupid problem, but I can't find a smart solution. Thanks for your time.