Comment # 16 on bug 1090480 from Tejas Guruswamy

(In reply to Nicholas Harvey from comment #15)
> Not to worry as I've rebooted and the redshift widget not only switches on
> and off correctly, but when on it no longer flickers.
> 
> That'll do me for now and I'll re-install redshift when the systemd update
> arrives to test the final fix.

Great, thanks. For clarification to anyone else reading:

systemctl --user disable redshift.service

is to be run as your/every user and

sudo systemctl --global disable redshift.service

is to be run as root.