public void Deploy(IUIHandler handler)
        {
            IUIHandler previous = CurrentHandler;
            if (handler != null)
            {
                handler.Deploy(this, previous);
            }

            CurrentHandler = handler;

            if (previous != null)
            {
                previous.Dismissed(this, handler);
            }

            if (handler != null)
            {
                handler.Deployed(this, previous);
            }
        }