public void Render(Rect rect) {
        FlexibleHeightRect r = new FlexibleHeightRect(rect);
        for (int i = 0; i < drawables.Count; i++) {
            float height = drawables[i].GetHeight();
            drawables[i].Render(r.Flex(height));
        }

    }
    public void Render(Rect rect)
    {
        FlexibleHeightRect r = new FlexibleHeightRect(rect);

        for (int i = 0; i < drawables.Count; i++)
        {
            float height = drawables[i].GetHeight();
            drawables[i].Render(r.Flex(height));
        }
    }