Cannot see login box on a locked screen

[Jens Herrmann]

1. Lock the screen
2. Try to log in and find the entire screen is white, except for the mouse cursor
3. Pressing any keys on the keyboard does not change anything
4. Pressing any mouse button makes the login screen visible the way expected.

This happens since the upgrade to 15.04. Its reproduceable always on my main notebook but not on a 2nd.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: lightdm 1.14.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
Date: Tue Apr 28 15:15:20 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-12-29 (119 days ago)
InstallationMedia: Xubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
SourcePackage: lightdm
UpgradeStatus: Upgraded to vivid on 2015-04-24 (4 days ago)

[Sebastien Bacher (seb128)]

Thank you for your bug report. What desktop environment do you use? Your installation media info states you are using xubuntu, is that the case stil? Do you get the same issue on the log screen at start?

[Jens Herrmann (bugs-u)]

Xubuntu is correct. It does not happen when I start and log in the first time, just when I lock the screen and try to log in afterwards.

[Andrew P. (kalgasnik)]

Could you try the latest development version?
https://launchpad.net/~lightdm-gtk-greeter-team/+archive/ubuntu/daily

[Jens Herrmann (bugs-u)]

I could try but Is there a chance to get back to the stable version after installing this PPA? I do need this machine for daily work.

[Andrew P. (kalgasnik)]

Do you have a multihead setup - notebook + external monitor?

[Jens Herrmann (bugs-u)]

Yes, a Thinkpad T500 on a dock type 2504

[Andrew P. (kalgasnik)]

As temporary workaround - you can add this option to your lightdm-gtk-greeter.conf:
active-monitor=0

0 - monitor which will be used to display greeter window, you can use name instead of number (LVDS0 or whatever `xrandr` shows).

Fix is commited to trunk version, so it will be a part of the next release.

[Jens Herrmann (bugs-u)]

I have now installed the PPA and can confirm that this bug is fixed. Thanks a lot for fixing this so quickly.