How to determine if a region's view and all its nested regions/views have finished loading

I'm integrating a Prism project with Silverlight's nav framework. Part of the task is to update the URL when an appropriate change happens in the app.

One area which I'm 开发者_如何学Pythonstuck with is how to determine if a region has finished 'loading' and all the appropriate view models have been instantiated.

I'm using view discovery and region.Activate to trigger the region. This method appears to return before all the view models have been created.

Thanks for your help!