Thanks for the help, @Brian. I thought about the package 'wayland', too, but trying to report a bug against it came out like this:
$ ubuntu-bug wayland dpkg-query: no packages found matching wayland -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to wayland in Ubuntu. https://bugs.launchpad.net/bugs/1727356 Title: Wayland does not start up To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/wayland/+bug/1727356/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp