Bug 323041

Power management settings from the Power Management KCM are not executed properly with regard to screen dimming and blanking. In particular, the screen goes blank at the screen dimming timeout instead of at the screen blanking timeout, at least when running on battery.

Reproducible: Always

Steps to Reproduce:
1. In the Power Management KCM, set a screen dimming timeout for the battery profile (not for low battery).
2. Set the screen blanking timeout to any time later than the screen dimming timeout (e.g., if the screen dimming timeout is 2 minutes, set the screen blanking timeout to 5 minutes).
3. Keep the computer idle on battery.
Actual Results:  
The screen goes blank at the end of the dimming timeout. For example, if the screen dimming timeout is 2 minutes and the blanking timeout is 5 minutes, the screen goes blank at the end of 2 minutes instead of 5 minutes.

Expected Results:  
The screen should only dim, not go blank, at the dimming timeout. It should go blank only at the end of the blanking timeout.

I experienced this erroneous behaviour on a Dell Inspiron N4110 laptop and also see it on a Lenovo G580 laptop, running 64-bit Kubuntu 13.04 with KDE SC 4.10.5.

The screen dims in stages, multiple times, before going blank. It may be that the screen does not actually go blank but that the brightness is reduced so much that it appears blank. However, I cannot verify this; on my system the screen is practically blank. It is not clear to me whether the KDE power management system is conflicting with or has overlapping functionality with any other Linux system power management policy such as DPMS. I have disabled DPMS and still see this behaviour.