title: Executing UI Code from ViewModel on MVVMCross
body: <p>I have just started using MvvmCross, but i didn't find any info about to how i can execute UI code from a ViewModel. </p>
  
  <p>On Caliburn there are coroutine so i can access the view and keep the ui code separated from the viewmodel code.
  on my first case i need to open a dialow from a command inside a ViewModel, what is the correct way?</p>
  
  <p>Right now i'm developing a WinRT app.</p>
  
  <p>Thanks</p>