public void Add(Actor actor)
 {
     if (actor.GetAlpha() == 1)
     {
         this.opaqueDrawList.Add(actor);
     }
     else
     {
         this.transparentDrawList.Add(actor);
     }
 }
        private void EventDispatcher_OpacityChanged(EventData eventData)
        {
            Actor actor = eventData.Sender as Actor;

            if (actor != null)
            {
                if (actor.GetAlpha() == 1) //was transparent but now opaque
                {
                    this.Remove(actor);
                    this.opaqueDrawList.Add(actor);
                }
                else //was opaque but now transparent
                {
                    this.Remove(actor);
                    this.transparentDrawList.Add(actor);
                }
            }
        }