Bug#836972: gnome-control-center could not get screen information anymore

[Andreas Henriksson]

Hello Jean-Marc.

Thanks for your swift reply.

On Thu, Sep 08, 2016 at 11:35:58AM +0200, Jean-Marc wrote:
> Thu, 8 Sep 2016 08:21:20 +0200
> Andreas Henriksson <andreas at fatal.se> écrivait :
> 
> > Control: tags -1 + unreproducible moreinfo
> > 
> > Hello Jean-Marc.
> 
> Hi Andreas,
> 
> > 
> > Thanks for your bug report.
> > [...]
> > I'm not able to reproduce your problem on neither of my two machines.
> 
> Clicking on the "Displays" icon in g-c-c drives to a sub-menu where I usually got infos on screens connected to my machines allowing to change screens' settings. Now, I got no screens' icons at all, just a message saying it is not posible to get screen info.
> 
> > Could you please quote the exact message you're seeing?
> 
> Exact message is: "Could not get screen information"

Thanks.

> 
> > Did you get any warning or error output when starting g-c-c from the command
> > line?
> 
> No message. I also started g-c-c in verbose mode but got nothing relevant.
> 
> > Interesting. Both of them running testing/stretch I guess?
> 
> Yes, both run the same Debian version.

... which is.... ? Stretch?!

> 
> > 
> > Could you please keep a tight watch on what you're updating the coming
> > days and if any of the updates makes the issue go away? If so please
> > report that information back. Not all of gnome 3.21/3.22 has yet migrated
> > to testing and it might be that we need a tighter dependency somewhere.
> 
> That's the problem of running in Strech.
> 
> Do you know which lib/sub-component g-c-c uses to get screens' info ?

https://codesearch.debian.net/search?q=Could+not+get+screen+information

See also:
http://sources.debian.net/src/gnome-desktop3/3.21.90-3/libgnome-desktop/gnome-rr.c/?hl=993#L993

Quoting something which might be relevant:

 * Returns: a unique #GnomeRRScreen instance, specific to the @screen, or NULL
 * if this could not be created, for instance if the driver does not support
 * Xrandr 1.2.  Each #GdkScreen thus has a single instance of #GnomeRRScreen.

> It can help me to look if upgrading one or more packages from Sid solve the problem.

Are you also using the proprietary using the proprietary nvidia driver
or which graphics driver are you using?

Could you also please tell me exactly which version of gnome-desktop3 you
have installed? dpkg -l 'libgnome-desktop-3-*'

Regards,
Andreas Henriksson