Although I do not know you application specifics I believe you have something like this:
So I assume the Toolbar Region contains your ToolBarView, and you change the content in your Main Region depending if the user has signed in or not (if the user has not signed in you show the
GuestView and if he has you show the AuthenticatedView).
I do not know the specifics of your application, but you usually create a module for every “atomic” piece of functionality of your application. Therefore, assuming they are in different modules
Publish an Event using the Event Aggregator in the module where the login is performed
once the user gets logged (in your scenario the module that has the ToolBarRegion,
but it could also be in a service).
Suscribe to the previously published event and handle it in the module where the
AuthenticatedView is placed (this is usually done in a presenter or model class).
Use View Injection, to place the
AuthenticatedView in the Main Region.
The Composite Application Guidance for WPF & Silverlight has some
Quickstarts that deal with the things I mentioned above:
View Injection Composition QuickStart (you can find it in the
Event Aggregation QuickStart (you can find in it the
Please let me know if this helps.