MediaPlayer.OnKeyDown() is implemented like so:
protected override void OnKeyDown(KeyRoutedEventArgs e)
if (e.Key == Windows.System.VirtualKey.Escape)
mediaElement.IsFullWindow = false;
so that pressing the Esc key should exit full window.
The issue we are having is that OnKeyDown is not called when the MediaElement is full window.
The sample app demonstrates this problem: put a breakpoint in this method and tab into the MTC and press escape and you will hit it, but when the MediaElement is full window you will not.
It seems that the input is not routed to MediaPlayer when full window.