[gtkada] Multiple instances of a window created from glade

[Arnaud Charlet]

> Seeing that there are two approaches and it at least appears that
> get_toplevel should be very straightforward is there
> any reason to avoid it and choose the other approach (as in GVD).

We use both approaches.
Get_Toplevel is more convenient, but will not return the expected
window for Gtk_Menu_Items. In this case, we use the object connect approach.

Arno