sudo apt-cache policy gnome-settings-daemon-schemas
gnome-settings-daemon-schemas:
  Installed: 3.8.6.1-0ubuntu11.2
  Candidate: 3.12.2-0ubuntu1~trusty3
  Version table:
     3.12.2-0ubuntu1~trusty3 0
        500 http://ppa.launchpad.net/gnome3-team/gnome3-staging/ubuntu/ trusty/main amd64 Packages
 *** 3.8.6.1-0ubuntu11.2 0
        500 http://gb.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.8.6.1-0ubuntu11 0
        500 http://gb.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages