after upgrade to 17.10, getting gnome-flashback by default under X

[Steve Langasek]

My laptop has been continuously upgraded (sometimes during development cycles, sometimes only after release) since Ubuntu 10.04.

After upgrade to 17.10, I initially used wayland, but ran into some problem with VT switching which led me to switch to X.

Upon switching to X, the default session option I'm given by gdm is gnome-flashback-session, running compiz by default.

This was a terrible experience, so I then purged compiz (knowing that it is no longer the supported wm for Ubuntu in 17.10). Launching the session again, I get gnome-flashback-session running metacity.

This is also a terrible experience, and AIUI not the experience users are expected to have by default. I am told that there is supposed to be an 'Ubuntu on X' session which should be the default.

I think the upgrade needs to try harder to ensure the correct session is used by default on upgrade. I don't believe gnome-flashback is something I ever manually configured; it is marked as 'manually installed' on my system, probably due to historic bugs in update-manager marking all packages as manually installed. I think either gdm should take this into account and deprioritize gnome-flashback as a session option in the absence of explicit configuration, or update-manager itself should take steps to ensure the package is removed on upgrade if it's not meant to be there.