private void AddComponent(Flat c) { var component = Flat.GetComponentLieIn(c); var room = component as Flat; if (room != null) { component.Add(new Room(new Rectangle() { Location = c.Rectangle.Location, Height = c.Rectangle.Height, Width = c.Rectangle.Width })); } else if (component is Room) { component.Add(new Furniture(new Rectangle() { Location = c.Rectangle.Location, Height = c.Rectangle.Height, Width = c.Rectangle.Width })); } else { errorLds.Text = "You can't add this shape"; } Draw(); PrintTree(); }