My Fn+Volume up/down key on a MacBook Pro late 2011 used to be functional as usual in Ubuntu 13.10. After upgrading to Ubuntu 14.04, I have to press the Fn+Alt+Volume up/down keyboard combination to do the same. The weird thing is when I set this function in System Settings -> Keyboard -> Shortcuts -> Sound and media, I only push Fn+Volume up/down. It sets the key binding correctly without Alt while not working with the Alt.
The problem is that an incorrect string is set in
Original (working) value:
~$ gsettings get org.gnome.settings-daemon.plugins.media-keys volume-up 'XF86AudioRaiseVolume'
After running "unity-control-center keyboard", and setting the shortcut for volume-up key:
~$ gsettings get org.gnome.settings-daemon.plugins.media-keys volume-up 'AudioRaiseVolume'
The new value misses the "XF86" part of the string, and does not work.
You can get the key working again by resetting the value, with:
~$ gsettings reset org.gnome.settings-daemon.plugins.media-keys volume-up ~$ gsettings reset org.gnome.settings-daemon.plugins.media-keys volume-down
The bug already reported: https://bugs.launchpad.net/ubuntu/+source/unity-control-center/+bug/1302885