public ObjectTweener(object targ, Curve curve)
        {
            if (targ == null) throw new System.ArgumentNullException("targ");
            if (curve == null) throw new System.ArgumentNullException("curve");
            if (curve.Tween != null) throw new System.ArgumentException("Tweener can only be created with an unregistered Curve.", "curve");

            _target = targ;
            _curve = curve;
            _curve.Init(this);
        }