GDM only displays on internal monitor even when external is available

[Rob King]

Binary package hint: gdm

My system has a docking station. When the system is docked with the lid closed, the external display is ignored. When the laptop lid is open, the display is mirrored. I can't have the lid closed under any circumstances.

Under 10.04, this worked correctly out of the box; under 10.10 beta, this failed immediately.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: gdm 2.30.5-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.35-20.29-generic 2.6.35.4
Uname: Linux 2.6.35-20-generic x86_64
Architecture: amd64
Date: Thu Sep 9 13:05:49 2010
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: gdm

[Rob King (jking)]

Further information: The issue appears to be that the external monitor is disabled when GDM loads. The Ubuntu boot splash screen appears, but when GDM starts, the external monitor is disabled.

If I log-in blindly, the external monitor is reactivated according to my GNOME settings (in this case, mirror displays).

[Rob King (jking)]

As a reminder, this wasn't a problem at all under 10.04; it started immediately upon upgrade to 10.10 beta.

[Rob King (jking)]

==== POTENTIAL WORKAROUND =====

The issue appears to be at least partially due to the fact that the per-user monitor configuration (/home/user/.config/monitors.xml) is not being installed systemwide. If I manually create /etc/gnome-settings-daemon/xrandr/ and run gnome-display-settings-install-systemwide, the issue is resolved.

This raises a few questions:

* Which package actually contains the root cause of the bug? It would appear to not be GDM's fault. I'm afraid I don't know enough about how Ubuntu is structured to find out for myself.

* What should be done upon install? The default, IMHO, should be to mirror all displays by default, so that if a user is installing on a laptop with a docking station, they don't loose their login display.

[Sebastien Bacher (seb128)]

Thank you for your bug report, the issue is due to the new gnome-settings-daemon