protected override bool ProcessCmdKey(ref Message msg, Keys keyData)//取消方向鍵對控件的焦點的控件，用自己自定義的函數處理各個方向鍵的處理函數
        {
            switch (keyData)
            {
                case Keys.Up:
                    UpKey();
                    return true;//不繼續處理
                case Keys.Down:
                    DownKey();
                    return true;
                case Keys.Left:
                    LeftKey();
                    return true;
                case Keys.Right:
                    RightKey();
                    return true;
            }
            return base.ProcessCmdKey(ref msg, keyData);
        }