Under certain circumstances adding a child to another displayobjectcontainer can lead to a parentNode = undefined error. Please see the appended demo code:

class Main extends Sprite {
	public function new() {
		super();

		var c:Sprite = new Sprite();

		var s:Sprite = new Sprite();
		var s2:Sprite = new Sprite();

		s.scrollRect = new Rectangle(0, 0, 10, 10);

		c.addChild(s2);

		c.addChild(s);
		c.addChild(s2);
	}
}
Merge pull request #14 from cyantree/hotfix/swap-surface

Error when swaping surfaces