Can't display images on a gtkmm-based gnome-panel applet

I ran into troubles trying to create a gnome-panel applet with gtkmm. I dealt with most of them, but I'm now kind of blocked.

Quick summary : I tried libpanelappletmm, but every program (even the examples supplied in the source code) segfaults when I try to add the applet in my panel. So I now use the C library (libpanel-applet). First I looked for a way to wrap the PanelApplet Gobject in a gtkmm C++-object, for example a Gtk::EventBox (PanelApplet inherits from GtkEventBox). I tried to cast it, but Glibmm kept throwing a warning ("Failed to wrap object 'PanelApplet'").

So I created a class "Info", inheriting from Gtk::HBox. In my main.cpp file I declare an instance of it, get the underlying GTK object (gobj method), and use the GTK+ functions to add it into the PanelApplet.

Here's my main.cpp.

#include <iostream>
#include <gtkmm.h>
#include <panel-applet.h>

#include "Info.hpp"

static void manage_timeboxes(BonoboUIComponent *uic, void *applet, const char* data) {
    std::cout << "manage" << std::endl;
}

static gboolean getApplet(PanelApplet *applet, const gchar *iid, gpointer data) {
    /*
       if(iid != "OAFIID:TimeboxingApplet")
       return false;
    */

    Glib::init();

    Gtk::Widget* content = new Info();
    gtk_container_add(GTK_CONTAINER(applet), content->gobj());

    static const char menu_xml[] =
        "<popup name=\"button3\">\n"
        "   <menuitem name=\"Manage\" "
        "             verb=\"manage_timeboxes\" "
        "           _label=\"_Gérer l'emploi du temps\"\n"
        "          pixtype=\"stock\" "
        "          pixname=\"gtk-properties\"/>\n"
        "</popup>\n";

    static const BonoboUIVerb linked_verbs[] = {
        BONOBO_UI_VERB ("manage_tim开发者_高级运维eboxes", manage_timeboxes),
        BONOBO_UI_VERB_END
    };

    panel_applet_setup_menu(applet, menu_xml, linked_verbs, data);

    gtk_widget_show_all(GTK_WIDGET(applet));

    return true;
}

PANEL_APPLET_BONOBO_FACTORY (
        "OAFIID:TimeboxingApplet_Factory",
        PANEL_TYPE_APPLET,
        "Timeboxing",
        "0.0",
        getApplet,
        NULL)

It works fine if I add labels or buttons in my Info object.

But then I tried to add an icon. My first try was adding a Gtk::Image as a property of Info.

Info.hpp

#ifndef TIMEBOXING_INFO_H
#define TIMEBOXING_INFO_H

#include <gtkmm/box.h>
#include <gtkmm/image.h>
#include <gtkmm/label.h>

class Info : public Gtk::HBox {
    public:
        Info();
        virtual ~Info(){};

    protected:
        Gtk::Image icon;
        Gtk::Label info;
};

#endif

Info.cpp

#include "Info.hpp"

#include <gtkmm/image.h>
#include <gtkmm/label.h>

Info::Info() : icon("/home/bastien/programmation/timeboxing-applet/icons/clock-24.png"), info("<b>En cours</b>") {
    info.set_use_markup();

    pack_start(icon);
    pack_start(info);

    show_all_children();
}

When I try to add the applet, I get this error and the program aborts :

glibmm:ERROR:objectbase.cc:78:void Glib::ObjectBase::initialize(GObject*): assertion failed: (gobject_ == castitem)

I commented "Gtk::Image icon" from Info.hpp, and I modified my constructor like this :

Info::Info() : info("<b>En cours</b>") {
    info.set_use_markup();

    Gtk::Image icon("/home/bastien/programmation/timeboxing-applet/icons/clock-24.png");

    pack_start(icon);
    pack_start(info);


    show_all_children();
}

I'm not getting the Glibmm error anymore, but the image isn't displayed. I tried with another file, with an icon from the stock, and even with a Gdk::Pixbuf.

Thank you in advance !

---

Well, strangely enough, it works if I create a pointer to Gtk::Image. If anyone has an explanation, it would be great !

Edit : apparently, I had to call Gtk::Main::init_gtkmm_internals. My wrapping troubles went away. I can wrap PanelApplet too, but if I use the resulting Gtk::EventBox* it doesn't display anything.