screenlock does not dpms off when screensaver is disabled

[Redsandro]

Desktop Environments like OpenBox and LXDE (in Lubuntu and Debian LXDE) rely on xscreensaver-command -lock to lock the screen. When locking the screen, the screen should turn off (e.g. backlight off).

But this only works if you have "Blank Screen Only" with a timeout selected in xscreensaver-demo. If you disable the screensaver, lock will turn the screen black but won't turn it off (backlight off) anymore.

This is undesirable. In certain usecases don't want to have a screensaver or blank screen after a timeout, e.g. for a media player. But we DO want to turn the screen off (completely off) when we lock the screen.

(Otherwise the HDMI channel remains 'open' and a multisource display device will keep selecting the black screen when another source/player/platform/console reboots and detaches it's HDMI signal for a few seconds.)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jarno Suni (jarnos)]

See the lxlock script by running 'cat $(which lxlock)' in terminal. There might be alternatives to xscreensaver depending on your LXDE version. E.g. you could run light-locker daemon instead of xscreensaver and the script would use 'light-locker-command -l' for locking thereafter.

[Jarno Suni (jarnos)]

Aa a workaround you could use the Blanc Screen Only mode and set timeouts to 0 in Advanced tab and enable Quick Power-off in Blank Only Mode. It sets off time internally to 65535 seconds. But it just powers off first time, not if you wake up screen while locked, right?

[Jarno Suni (jarnos)]

Oh, you would have to set Blank After timeout to maximum, 720 minutes, too.

[Jarno Suni (jarnos)]

Xfce has a mode switch (normal/presentation) in Xfce Power Manager's tray icon menu, but it does not work well with xscreensaver. I have been working on xflock4 script that is used by Xfce for locking. My version will save the dpms state, use decent state while locked, and restore the old state, when unlocked; the system works by non-forking lockers only (i.e. lockers that run on foreground). The script could be used as lxlock if modified slightly. See
https://bugzilla.xfce.org/show_bug.cgi?id=10217