private void ModelStarChangedEventHandler(object sender, Model.Event_Arguments.StarChangedEventArgs e) { if (e.Disappeared && _stars.ContainsKey(e.Point)) { _sprites.Remove(_stars[e.Point]); } else { if (!_stars.ContainsKey(e.Point)) { FrameworkElement newStar = InvadersHelper.StarControlFactory(Scale) as FrameworkElement; _stars.Add(e.Point, newStar); _sprites.Add(newStar); InvadersHelper.RepositionElement(newStar, e.Point.X * Scale, e.Point.Y * Scale); InvadersHelper.SendToBack(newStar); } } }