Bug#836939: gnome-settings-daemon: Screen brightness defaults to a very low value and can't be changed with Function Keys, Applet or in System Settings

[Christophe Troestler]

With that upgrade, the sound keys are no longer working.  The menu 
slider does though.

On 2016-09-09, Christophe Troestler wrote:
> 
> 
> Upgrading mutter
> 
>     apt install mutter -t unstable
> 
> fixes the problem.