I have a Mate session with one user on vt7 started via systemd and lightdm. I also run second Mate session with a different user on vt1 started with startx. For the second instance .xinitrc contains only the line “exec mate-session”.
When I switch from vt1 to vt7 X crashes and sends me back to the gtk greeter. This did not happen in 16.04. I can work around this by switching to any other vt that isn’t running X before switching to vt7.
This is only a minor annoyance but I’d like to understand why things are different in 16.10.
Everything else in 16.10 has worked great!