how to connect Gio::SimpleAction signal

[Marty Moore <memoore gunnison com>]

Hi all,
I've been trying to create a dynamic menu in gtkmm3, using the
Gio::MenuModel classes. I can get the Gtk::MenuButton to popup the
Gio::MenuItem, and the Item responds to the click. Unfortunately, I
can't figure out how to connect the Gio::SimpleAction to my signal
handler. The only example I can find is a Gtk+ one, and it uses
different functions.

The problem is thet the prototype for the signal connection is:
 void on_my_activate(const Glib::VariantBase& parameter)

I've tried various combinations, but I can't get the connection to
work. I don't know how to handle the VariantBase.

I'd appreciate a nudge in the right direction.
Thanks,
Marty

Here's my code:

xwin.h:
 
> #include <iostream>
> #include <gtkmm.h>
> #include <giomm/menu.h>
> #include <giomm/simpleaction.h>
>
>
> using std::cout;
> using std::endl;
>
> namespace geode
> {
>
>
>     class Gui : public Gtk::Window
>     {
>     public:
>       Gui();
>       virtual ~Gui();
>
>       void create_cv_menu ();
>
>     protected:
> //    void on_cv_menu_clicked( guint& index);
> //            void on_cv_menu_clicked();
> //    void on_cv_menu_clicked(guint& index);
>       void on_cv_menu_clicked( guint& index)
> //        const Glib::Variant<guint32>& parameter)
>           { cout << "on_cv_clicked 0:" << endl; }     
>
>       //Child widgets:
>       Gtk::Box m_Box;
>       Glib::RefPtr<Gio::MenuModel> menumodel;
>       Glib::RefPtr<Gio::Menu> giomenu;
>       Gtk::MenuButton mbut1;
>       Glib::RefPtr<Gio::SimpleAction> ref_action;
>     }; // end class Gui
>     
> } // end namespace geode
> #endif //GTKMM_EXAMPLEWINDOW_H

xwin.cpp:

#include "xwin.h"
#include <iostream>

namespace geode
{
    
//CCCCCC GUI CCCCCCCCCCCCCCCC
    Gui::Gui()
        : m_Box(Gtk::ORIENTATION_VERTICAL),
          mbut1()
    {
        set_title("menu test");
        set_default_size(200, 200);
        mbut1.set_label("button 1");
        add(m_Box);
        create_cv_menu();
        m_Box.pack_start(mbut1, Gtk::PACK_SHRINK, 5);
        mbut1.set_menu_model(menumodel);
        show_all_children();
    }

    Gui::~Gui()
    {
    }

    //FFFFFF GUI FFFFFFFFFFFFFFFF
    void Gui::create_cv_menu()
    {
        cout << "Gui create_cv_menu 0:" << endl;
        guint32 index = 1;
        giomenu = Gio::Menu::create();
        menumodel = giomenu;
        giomenu->append("FRONT");
        ref_action = Gio::SimpleAction::create("FRONT");
        ref_action->signal_activate().connect(
            sigc::bind<guint32>(
        sigc::mem_fun(*this, &Gui::on_cv_menu_clicked), index));

// this is Gio::SimpleAction signal_activate handler prototype
//    void on_my_activate(const Glib::VariantBase& parameter)

        cout << "Gui create_cv_menu 99:" << endl;
    }
/*
//FFFFFF GUI FFFFFFFFFFFFFFFF
    void Gui::on_cv_menu_clicked(const Glib::Variant<guint32>& index)
    {
        cout << "Gui on_cv_menu_clicked 0: index = " << index << endl;

//      return true;
    }
*/
} // end namespace geode