Marko - try modifying /etc/systemd/logind.conf as discussed in https://bugs.launchpad.net/ubuntu/+source/xubuntu-default-settings/+bug/1303736/comments/118.
Marko - try modifying /etc/systemd/ logind. conf as discussed in https:/ /bugs.launchpad .net/ubuntu/ +source/ xubuntu- default- settings/ +bug/1303736/ comments/ 118.