[gtkmm] Fixed container and Gtk::Container::foreach

["Enrico Costanza" <ec142 york ac uk>]

Dear all,

I am trying to use the Gtk::Fixed container because I need to specify
precisely the coordinate of my objects on screen.

Can anyone give me an example of how to use the foreach function in
Gtk::Container? I did not manage to find anything in the examples nor in the
documentation.

Thank you in advance,
Enrico Costanza