C# 控件预处理键盘命令

public class MyRichTextbox : RichTextBox
    {
        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            if ((keyData == (Keys.Control | Keys.Enter)))
            {
                MessageBox.Show("ctrl+enter");

                return true;
            }
            else if (keyData==Keys.F5)
            {
                MessageBox.Show("f5");
                return true;
            }
            else
            {
                return base.ProcessCmdKey(ref msg, keyData);
            }
        }
    }