[Pkg-xfce-devel] Bug#828204: Bug#828204: light-locker: Without chrome running, obeys xfce4-power-manager. With chrome, usually doesn't.

[Fred Korz]

On 06/26/2016 03:07 PM, Yves-Alexis Perez wrote:
> On sam., 2016-06-25 at 22:05 -0400, Fred Korz wrote:
>> Since then, if google chrome (stable) is not running, power management on the
>> display works just as set.
>>
>> However, if google chrome is running, for a while display blanking and turndown
>> works as configured, but eventually blanking doesn't work.
> My first guess would be that google chrome uses inhibition to prevent screen
> blanking/locking. Does it matter which tabs are open in google chrome?
>
> Regards,

I had thought that too, that perhaps vlc were using inhibition, but 
shutting down vlc or not starting it had no effect.

As to chrome, not that I can tell if a particular tab is causing it.  
With 20 windows averaging 10 tabs/window, and a minimum of 3 minutes 
wait per sample to tell the outcome, that's not really practical.  That 
would be O(10) hours worst case, O(5) hours if found half way through.  
(Yes, I could use binary rather than linear search, but I'd have to 
figure out a way to store and restore the serious amount of state held 
in those windows and tabs.)

I suspect that there is a combination of (1) inhibition, which I don't 
know a practical way of finding, but hoped the package maintainers could 
suggest so I could chase it down, and (2) an assumption in light-locker 
of an installed screen locking which is violated when there's no 
screensaver installed (which seems to run counter to the 
self-containment goal of light-locker and the lack of a package 
dependency on any screensaver).

To that second point:

    If I run 'light-locker-command --lock', I get blanking, light off, 
power minimization and locking.

    If I run 'light-locker-command --activate', which I believe the man 
page suggests will do all the above except lock, instead it goes through 
as if it expected to rely on a screen locker as a barrier but it comes 
back with the complaint, previously cited above, about locker failure.  
I tried all the permutations on xfce4-power-manager-setting of 
"Automatically lock the session" in {"Never", "When screensaver is 
activated",
"When screensaver is deactivated"} crossed with "Lock screen when system 
is going for sleep" in {checked, unchecked}.

Fred


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