xset s on & xset dpms &
these had no effect. after replacing xscrnsvr and xfce4-pwrmgr with those in autostart, and rebooting, the screen did not blank at all any more. well not after 25min at least.
i tried from the terminal:
xset dpms force off xset dpms force suspend xset dpms force standby xset +dpms xset -dpms xset s 20
- they all worked, but immediately after blanking and backlight off, it unblanks again.
i tried killing off processes 1 by 1 and retrying xset s 20.
killing tint2, conky, iceweasel(firefox-bin), transmission, ...
still the same.
i searched "laptop power manage" in synaptic but only xfce4-power-mgr is installed.
so before i start shooting in the dark, is there anything else i can do?
yes i totally agree with that, but no, this is not the problem here.
the problem is that regrdless of which program i use for switching off the backlight, the screen lights up again immediately.
i tried disabling either xfce4-pwrmgmt or xscrsvr and also both but the problem persists.
and with disabling i mean commenting it out in autostart and rebooting.
right now i'm running neither, just some xset-magic as described by machinebacon - but the problem persists. duh.