Hooking Into the Navigation Pane Click Event

I'd like to display content in a control outside of the Navigation Bar when I click on one of the Navigation Pane "buttons". I notice in the documentation that the Navigation Pane has no events and the NavigationBar has none specifically geared toward this. The NavigationBar *does* inherit the SelectionChanged event (from Selector), but I'm at a loss as to how to cast the sender parm in the handler.

Is the SelectionChanged event the best event to handle this? If not, what would be the proper event and how should I go about this (a bit of code would be helpful)?

Thanks,

Chris