Docs

In-depth how-to’s on PoshGUI features

WPF – Multi-Page Forms

 

You can design applications with multiple pages using the tab control

You can set the visibility of tab items to Hidden in the XAML panel:

<TabItem Name="LoadingScreen" Visibility="Collapsed">

This will hide the navigation part of the Tab Control
You can then implement your custom navigation, by programmatically changing the SelectedIndex property of the tab control

Giving you the effect of an app with multiple screens