private void MoveLeft(object sender, RoutedEventArgs e)
 {
     if (Grid.Margin.Left > 0)
     {
         Grid.Margin = new Thickness(Grid.Margin.Left - 100, 0, 0, 0);
     }
     else
     {
         Grid.Margin = new Thickness(0, 0, Grid.Margin.Right + 100, 0);
         Scr.ScrollToHorizontalOffset(Scr.HorizontalOffset + 100);
     }
 }