title: MvvmCross: Does ShowViewModel always construct new instances?
body: <p>Whenever I call ShowViewModel, somehow a ViewModel and a View of the requested types are retrieved and are bound together for display on the screen.  When are new instances of the ViewModel and View created versus looked up and retrieved from a cache somewhere?  If new instances are always created and I choose to make my own cache to prevent multiple instances, then how do I show my cached ViewModel instance?</p>