private static void keyAnswer(IntPtr ctx, String pMac, int key)
        {
            GCHandle thisHandle = GCHandle.FromIntPtr(ctx);
            RbtNet   rbtNetThis = (RbtNet)thisHandle.Target;

            if (rbtNetThis != null && rbtNetThis.KeyAnswerEvt_ != null)
            {
                rbtNetThis.KeyAnswerEvt_(ctx, pMac, key);
            }
        }