void UpdateClipRect()
{
if (scrollPane == null)
{
float w = this.width - (_margin.left + _margin.right);
float h = this.height - (_margin.top + _margin.bottom);
rootContainer.clipRect = new Rect(_margin.left, _margin.top, w, h);
}
else
rootContainer.clipRect = new Rect(0, 0, this.width, this.height);
}