title: WPF How to call some logic in a parent ViewModel from a child ViewModel in MVVM
body: <p>I'm using Prism.
  I have a tabcontrol in my parent View.  I have two tabs in my tab control.  Each tab has a different View.  Each tab has a button which may or may not (depending on some internal logic) cause the tabcontrol to switch to a different tab.  What is the best practice for setting up an architecture like this?</p>
  
  <p>I am against using the EventAggregator because I believe its sloppy and is easy to misuse.
  Is there another way to do this?  Should I use a RoutedCommand or events?  </p>
  
  <p>I'm also going to be sharing information between the tabs, but I want them to be loosely coupled and have distinct ViewModels.  Any thoughts, suggestions, or criticism?</p>
  
  <p>Thanks!
  Brett</p>