C#自定义控件按钮事件有关问题

        private KeyEventHandler mOnKeyDown;                   //事件触发器 
        /// <summary>
        /// 处理单击事件
        /// </summary>
        public event KeyEventHandler KeyDownEventHandler
        {
            add
            {
                mOnKeyDown += value;
            }
            remove
            {
                mOnKeyDown = value;
            }
        }
        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (mOnKeyDown != null)
            {
                mOnKeyDown.Invoke(this, e);
            }
        }