struct MyApp {
    typedef MyApp CLASSNAME;

    Vector<String> top;
    Vector< Vector<String> > submenu;

    void Action(int top, int i) { /* some action */ }

    void SubMenu(Bar& bar, int top) {
      const Vector<String>& sm = submenu[top];
      for(int i = 0; i < sm.GetCount(); i++)
          bar.Add(sm[i], THISBACK2(Action, top, i));
    }

    void MainMenu(Bar& bar) {
       for(int i = 0; i < top.GetCount(); i++)
           bar.Add(top[i], THISBACK1(SubMenu, i));
    }

    ....
};