private void Form2_Load(object sender, EventArgs e)
{
    CreateMenu();
}

private void CreateMenu()
{
    //定义菜单条
    Bar bar = new Bar("Menu Bar");
    bar.MenuBar = true;
    bar.Stretch = true;
    bar.Style = eDotNetBarStyle.Office2003;
    dotNetBarManager1.Bars.Add(bar); //添加到dotNetBarManager1对象
    bar.DockSide = eDockSide.Top;    //设置Dock样式

    System.Diagnostics.Stopwatch stopwatch = new System.Diagnostics.Stopwatch();
    stopwatch.Start(); //  开始监视代码运行时间

    var listMenu = GetButtonItem(0);
    listMenu.ToList().ForEach(x => bar.Items.Add(x));
    bar.RecalcLayout(); //重绘布局

    stopwatch.Stop(); //  停止监视
    TimeSpan timespan = stopwatch.Elapsed; //  获取当前实例测量得出的总时间

    this.labelX1.Text = "生成菜单耗时" + timespan.TotalSeconds.ToString() + "毫秒";
    //textBoxX1.LostFocus += (s, e) => { MessageBox.Show("失去焦点"); };
}

public class JsonTuple<T1, T2>
{
    public T1 Item1 { get; set; }
    public T2 Item2 { get; set; }
    public KeyValuePair<Int32, Int32> KvType { get; set; }
    public Boolean Tag { get; set; }

    public JsonTuple(T1 item1, T2 item2, KeyValuePair<Int32, Int32> kvType, bool tag)
    {
        this.Item1 = item1;
        this.Item2 = item2;
        this.KvType = kvType;
        this.Tag = tag;
    }
    public JsonTuple(T1 item1, T2 item2, bool tag)
        : this(item1, item2, new KeyValuePair<int, int>(0, 0), tag)
    {
    }
}

private List<JsonTuple<string, string>> GetMenuSetter()
{
    List<JsonTuple<string, string>> listMenu = new List<JsonTuple<string, string>>
    {
        //有&会在字体下面显示下划线
        new JsonTuple<string,string>("bFile","&File",new KeyValuePair<int, int>(1,0),false),
        new JsonTuple<string,string>("bOpen","Open",new KeyValuePair<int, int>(2,1),false),
        new JsonTuple<string,string>("bClose","&Close",new KeyValuePair<int, int>(3,1),false),
        new JsonTuple<string,string>("bExit","&Exit",new KeyValuePair<int, int>(4,1),true),
        //====================================================
        new JsonTuple<string,string>("bCut","&Cut",new KeyValuePair<int, int>(5,0),false),
        new JsonTuple<string,string>("bCopy","&Copy",new KeyValuePair<int, int>(6,5),false),
        new JsonTuple<string,string>("bPaste","&Paste",new KeyValuePair<int, int>(7,5),false),
        new JsonTuple<string,string>("bClear","&Clear",new KeyValuePair<int, int>(8,5),true),

    };
    return listMenu;
}

private IEnumerable<ButtonItem> GetButtonItem(int pid)
{
    var listMenu = GetMenuSetter();

    var query = listMenu.Where(x => x.KvType.Value == pid).Select(x =>
    {
        var bi = new ButtonItem(x.Item1, x.Item2);
        bi.Tag = x.KvType; //标记
        bi.BeginGroup = x.Tag;
        return bi;
    });

    var plist = query.ToList();

    plist
        .ForEach(
            x => x
                .SubItems
                .AddRange(
                    GetButtonItem(((KeyValuePair<int, int>)x.Tag).Key).ToArray()
                )
        );

    return plist;
}

winfrom递归生成菜单，支持多级嵌套