public GraphicsCanvasRenderer(IGraphicsElementContainer container, Action onInvalidate)
        {
            children            = new GraphicsElementCollection(container);
            onInvalidateSurface = onInvalidate;

            renderSuspendCount = 0;
            renderPending      = false;
        }
 public GraphicsElement()
 {
     children = new GraphicsElementCollection(this);
 }