Switching users while screen is locked freezes the screen locker

[Jean-Baptiste Lallement]

Binary package hint: lightdm

TEST CASE:
1. Login
2. Press CTRL+ALT+L to lock the screen
3. Wake up the screen by pressing any key or moving the mouse
4. Click on 'Switch User'

Result:
The 'Switch user' button stay pressed for a moment, then the password dialog disappear and nothing else can be done from that screen. (Cure: Switch to a console, kill X and restart lightdm)

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: lightdm 0.3.7-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.39-3.10-generic 2.6.39
Uname: Linux 2.6.39-3-generic i686
Architecture: i386
Date: Thu Jun 2 16:40:49 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110209)
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

[Robert Ancell (robert-ancell)]

I don't get the freeze, but the switch doesn't occur.

Looking in the code for gnome-screensaver, the code is in src/gs-lock-plug.c do_user_switch (). It calls gdmflexiserver which obviously doesn't work with LightDM. Note that gnome-screensaver is planned to be integrated into GNOME Shell, so this may need to be fixed in Unity depending on what solution Ubuntu chooses.

[Robert Ancell (robert-ancell)]

This was fixed by Michael Terry in 0.9.3, lightdm now provides a gdmflexiserver for backwards compatibility. In the future hopefully we will have a common interface for switching and we can drop this.