Snapped

public MainPage()
        {
            this.InitializeComponent();
            LayoutUpdated += MainPage_LayoutUpdated;
        }
        void MainPage_LayoutUpdated(object sender, object e)
        {
            var newViewState = Windows.UI.ViewManagement.ApplicationView.Value;

            if (newViewState == Windows.UI.ViewManagement.ApplicationViewState.Snapped)
            {

                A.Visibility = Visibility.Collapsed;
                B.Visibility = Visibility.Visible;

            }

            else
            {
                A.Visibility = Visibility.Visible;
                B.Visibility = Visibility.Collapsed;

            }
        }