Seems there's an easy way to diagnose this. Just use the dbus-monitor
to see what events are generated on your system when the screensaver
activates and note the member name. Substitute that into the script and
it should be triggered on the correct event generated on your system.
In 9.04 and
Did you set your screensaver to activate? The script works by getting
triggered by the screensaver event. Once triggered, it calls a command
to set the monitor to standby.
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Power Manager Not putting Monitor to Sleep
https://bugs.launchpad.net/bugs/550054
You received this bug notification
I had this same issue with Karmic. It seems gnome-power-manager gets
confused when the laptop lid is closed and an external monitor is used
instead as the primary display. I wrote a script to set the monitor to
standby and I run it in System,Preferences,Startup Applications.
$ cat