DotNetBar TextBoxDropDown响应按键事件

textBoxDropDownHelp.TextBox.KeyDown += new KeyEventHandler(textBoxDropDownHelp_KeyDown);

private void textBoxDropDownHelp_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode==Keys.Enter)
            {
                textBoxDropDownHelp.ShowDropDown();
            }
        }