This link may help (tells how to use Dbus to get notifications of screen idle state changes):
http://live.gnome.org/GnomeScreensaver/FrequentlyAskedQuestions#head-ac43c8f33bc700a5e298e6a82ded0e8bb9b33043
This link may help (tells how to use Dbus to get notifications of screen idle state changes):
http:// live.gnome. org/GnomeScreen saver/Frequentl yAskedQuestions #head-ac43c8f33 bc700a5e298e6a8 2ded0e8bb9b3304 3