bug#22952: MacBook2,1 brightness control requires root privileges

[Albin]

Hi,

I've discovered that the non-working brightness controls for the
MacBook2,1 are due to insufficient permissions.

The first indication of this was that I could change brightness by
running the program redshift with root permissions (`sudo redshift`).

Today I was presented with this dialog box in GNOME 3 after having
pressed one of the brightness-control keys:

"Authentication is needed to run
'/gnu/store/[...]-gnome-settings-daemon-3.18.2/libexec/gsd-backlight-helper'
as the super user.

Administrator
Password [__________]"

I tried to input both the user password and the root password but none
of this this had any effect. When I back into GNOME 3 as root, however,
the brightness controls were working.

Does anyone have a suggestion what I could try to give the various
brightness control programs (for GNOME 3, Xfce, etc.) the required
permissions without having to be logged in as root?

Cheers!

Albin