Detecting user logout in GTK+ application

[phan <phanyx o2 pl>]

Hello,

is there any signal emitted, when user is logging out or system is going to restart? In both cases applications seems to be closed in a brutal way (destructors are not run) and catching SIGTERM or SIGINT is futile. I wonder, if it's possible to perform some actions (e.g. saving some files) before user logout?

On this site: 
http://stackoverflow.com/questions/2490166/detect-user-logout-shutdown-in-python-gtk-under-linux-sigterm-hup-not-recei
someone solved the problem using libgnomeui, but it is now deprecated. Is there any other way to achieve the same result?

Regards,
phan