ppc 上下键切换控件焦点

       找了很长时间也没有找到解决方法，只能自己写一个很笨的方法了,相信大家一看就懂了！

        private int _CurrentTabIndex = 0;
        private int _TabIndexMax = 4;
        private int _TabIndexMin = 0;

        private void Form1_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Up && _CurrentTabIndex > _TabIndexMin)
            {               
                _CurrentTabIndex--;              
               
            }
            else if (e.KeyCode == Keys.Down && _CurrentTabIndex < _TabIndexMax )
            {
                _CurrentTabIndex++;
            }

            foreach (Control ctrl in this.Controls)
            {
                if (ctrl.TabIndex == _CurrentTabIndex)
                {
                    ctrl.Focus();
                    break;
                }
            }
        }