MSDN explains the RootVisual can only be set one time from code:
You can set the value of the RootVisual property only one time from code, although you get its value any number of times.
http://msdn.microsoft.com/en-us/library/system.windows.application.rootvisual(VS.95).aspx
But we can set it to a UserControl that can switch it’s own content, as explained in the blog post:
http://craign.net/2008/03/11/how-to-switch-silverlight-usercontrols/
I used this procedure to start with a progressIndicator and after authenticating the user and loading the user properties, showing the masterpage.
Tags: Silverlight
