Appmenu gets deactivated after application window is hidden (gtkmm)

[Tom Jaeger]

This happens on quantal, when running outside of a desktop environment that displays the appmenu itself (e.g. gnome classic).

Steps to reproduce:
1. Compile the attached test case and run it
$ g++ menu.cc `pkg-config gtkmm-3.0 --cflags --libs` -o menu && ./menu

2. Hide the application using the appmenu. The following warning appears:
(menu:23356): Gtk-WARNING **: GtkMenuBar 0x1396090 is mapped but visible=1 child_visible=1 parent gtkmm__GtkApplicationWindow 0x1388040 mapped=0

3. Show the application again by executing ./menu from a different terminal window. The entry in the appmenu is now deactivated.

[Tom Jaeger (thjaeger)]

Interestingly enough, when I write the app in vala instead, I get the same error message but the appmenu stays functional.

[Tom Jaeger (thjaeger)]

The error message doesn't necessarily have to do anything with the menu being deactivated. Even after applying a workaround that gets rid of the message (by hiding the menu before hiding the window), the menu still refuses to work after hiding the window and showing it again.

I'm a at a loss as to how to debug this. All I can say so far is that it is not the action that gets deactivated, so it must have something to do with the menu.