...
AddFrame(menu);
menu.Set(THISBACK(Menu));
...

...
private:

MenuBar menu;

void Menu(Bar& menu) {
    menu.Add("File", THISBACK(File));
}

void File(Bar& menu) {
    menu.Add("New", THISBACK(New));
    menu.MenuSeparator();
    menu.Add("Load", THISBACK1(Load, "nic"));  // "nic" - just a dummy thing
    menu.Add("Save", THISBACK(Save));
    menu.MenuSeparator();
    menu.Add("Load scheme", THISBACK1(LoadSch, false));
    menu.Add("Save scheme", THISBACK(SaveSch));
    menu.MenuSeparator();
    menu.Add("Exit", THISBACK(Close));  // Close() - original "API" function
}

// definition of these is in .cpp file
void Reset();
void New();
public:
void Load(String file);     // public because of calling before .Run() in main
void LoadSch(bool start);
private:
void Save();
void SaveSch();
...