Applications for pages are designed to work inside the container. The container may be a browser or your own window.
To container for handling full screen mode.
edit Ok, I get it. When there is no window, the environment creates for you. You can access the window with Application.MainWindow, and you can change the properties this way (vb code):
Private Sub Application_Activated(sender As Object, e As System.EventArgs) Handles Me.Activated
Me.MainWindow.WindowState = WindowState.Maximized
Me.MainWindow.WindowStyle = WindowStyle.None
End Sub
, , , .
WPF http://www.paulstovell.com/wpf-navigation