private void SingleMediaElement_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
    {
        SingleMediaElement.IsFullWindow = !SingleMediaElement.IsFullWindow;
    }

private void SingleMediaElement_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
{
        var view = ApplicationView.GetForCurrentView();

        if (view.IsFullScreenMode)
            view.ExitFullScreenMode();
        else
            view.TryEnterFullScreenMode();
}