I just found some log messages from Unity panel service in /var/log/syslog. I've no clue if they are related to the problem, but maybe ...
Oct 19 21:43:58 bbc-000098 unity-panel-ser[4339]: Sync failed, now we've got extra layout nodes. Oct 19 21:45:29 bbc-000098 unity-panel-ser[4339]: message repeated 8537 times: [ Sync failed, now we've got extra layout nodes.] ** Also affects: compiz Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1634220 Title: Wallpaper does not resize correctly when adding external display To manage notifications about this bug go to: https://bugs.launchpad.net/compiz/+bug/1634220/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs