Comment 13 for bug 448438

In the hope that it can help as per previous comment, here are some
steps for reproducing:

- in gnome-power-preferences, set the screen to blank after 1 minute of
inactivity
- (optional?): in gnome-screensaver-preferences, set the session to go
idle/screensaver to activate at 1 minute

Now, logout and login (to make sure you have a clean session). Then:
1. do nothing for 2 minutes. The screen should blank. If you have
empathy running, the status should become "Away"
2. move the mouse or type something, the session becomes active again
3. to break this normal cycle, open any image (with the default image
viewer, eog), go in fullscreen (F11) or slideshow mode (F5), the message
'Method "InhibitActivation" with signature "s" on interface
"org.gnome.ScreenSaver" doesn't exist' will be printed in the terminal
if you ran it from a terminal.**
4. close eog*
5. wait as long as you want, the session will not go idle.

*: step 3 can (at the time I am writing this) be tested also by playing
any movie with totem, then exiting totem
**: for some reason, this happens on my generic desktop machine, but not
on my lpia netbook.