The Mvvm Platform for Xamarin.iOS, Xamarin.Android, WindowsPhone, WindowsStore, WPF and Mac. Includes databinding support for Android XML, for iOS XIBs and for MonoTouch.Dialog.
For now, the OnBackPressed() is called in OnOptionsItemSelected() to trigger the same behavior of a back button pressed which doesn't cause an issue.
This should be improved to properly handle the case of an ActionBar home button pressed