public void Handle_MouseDown(object sender, MouseEventArgs args) { slider.Fill = new SolidColorBrush(Colors.Green); Rectangle item = sender as Rectangle; mouseHorizontalPosition = args.GetPosition(null).X; BelowMap.Extent = AboveMap.Extent; BelowMap.Visibility = Visibility.Visible; isMouseCaptured = true; item.CaptureMouse(); }