[gtkmm] Why this "Gtk-WARNING" message when using a Gtk::Entry ?

["Nad" <enidan971 free fr>]

Hello,

I'm using gtkmm 2.4.3 for Windows.
When I show a Gtk::Dialog which have a gtk::Entry, I've got following
message :
    (logigraphe.exe:1236):Gtk-WARNING **: Le module sp\xe9cifi\xe9 est
introuvable.

    (logigraphe.exe:1236):Gtk-WARNING **: Loading IM context type 'cedilla'
failed
Translation for first sentence : Can't find specified module.

This is my code :
        Gtk::Dialog dialog(gettext("Custom size ..."),
                           *m_window,
                           false,
                           false);
        Gtk::Table entryTable(2, 2);
        dialog.get_vbox()->add(entryTable);
        Gtk::Entry rowEntry;
        entryTable.attach(rowEntry,
                    1,
                    2,
                    0,
                    1,
                    Gtk::FILL | Gtk::EXPAND,
                    Gtk::FILL | Gtk::EXPAND,
                    2,
                    2);
        dialog.show_all();
        int response = dialog.run();

Thanks !