private async void LessonContainer_StylusDown(object sender, StylusDownEventArgs e)
{
// If touch-and-hold (within 9px radius circle, over 700ms)
if (await TouchHelper.StylusHold(e, LessonContainer, 700, 9))
{
// Opens RadialMenu
layerStack.OpenRadialMenu(layerStack.Viewport.GetViewport(), e.GetPosition(LessonContainer),
RadialMenuState.Levels.Main);
}
}