protected MixedGraphicsControlHandler(DrawMapper?drawMapper, PropertyMapper mapper) : base(mapper ?? ViewHandler.Mapper)
 {
     _drawMapper = drawMapper ?? new DrawMapper <TViewDrawable, TVirtualView>(ViewHandler.DrawMapper);
 }
 protected MixedGraphicsControlHandler() : base(ViewHandler.Mapper)
 {
     _drawMapper = ViewHandler.DrawMapper;
 }