gnome-settings-daemon grabs multimedia keys and drops mute since upgrade 16.04 - Ask Ubuntu

i have thinkpad x1 (1st gen) running ubuntu (previously on 14.04)

it has multimedia buttons on side for: xf86launch1, xf86audiomute, xf86audioraisevolume, xf86lowervolume , xf86audiomicmute. used work fine in 14.04, extent little orange light inside 'mute' key come on when muted , turn off when not.

i upgraded 16.04 , none of them worked anymore.

i realized getting grabbed (but not used by) keyboard shortcuts accessible gnome-control-center or unity-control-center.

when turned off keyboard shortcuts media keys, able see keycodes xev, , hence able use xbindkeys hack of solution.

all except input mute, still isn't working. check acpi_listen , see that buttonpress being registered, other media keys, when press it, see:

(gnome-settings-daemon:14711): glib-gio-warning **: dropping signal acceleratoractivated of type (uuu) since type expected interface (ua{sv}) 

when kill gnome-settings-daemon can see input mute key in xev , grab needed.

how can keep gnome-settings-daemon trying (and failing to) grab key?

if you're not running gnome-shell desktop environment, have issues media keys. they're configured , handled gnome-settings-daemon, grabbed gnome-shell since this commit in 2013.

to restore old behavior without running gnome-shell or unity, must install , run shim program grab , forward keys.

for media keys functionality, such program available in arch linux aur package gnome-settings-daemon-compat. package provides executable /usr/lib/gnome-settings-daemon/gnome-fallback-media-keys-helper, provides support media keys in desktop environment/window manager.

you need add dependency of gnome session or otherwise have run @ session init. i'm not sure if it's packaged ubuntu, or if can run unity-fallback-media-keys-helper instead (i don't have either installed check).