Ubuntu
unity-greeter package

After upgrading to 16.04, greeter does not handle double screen anymore

Bug #1610543 reported by Alexis Scheuer
6
This bug affects 1 person
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unity-greeter (Ubuntu)
New
Undecided
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Bug Description

Hello.

I upgraded my laptop from 14.04 to 16.04 (Ubuntu 16.04.1 LTS) a few days ago. Since then, the login screen doe not appear anymore when I have a dual monitor (either connected to VGA port or docked via VGA or HDMI), both screen are black, showing only the cursor.

When I switch back to one monitor (disconnecting the VGA monitor or undocking), the laptop turns to sleep (?!?). After waking it up, I got the screen, can login, connect back the second monitor and activate it (with xrandr).

If I connect the second monitor when the computer sleeps, and wake it up, I then have the display, but without the login window (it appears as soon as I disconnect the monitor).

The software lightdm is up to date (1.18.2-0ubuntu1).

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lightdm 1.18.2-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: XFCE
Date: Sat Aug 6 16:50:11 2016
InstallationDate: Installed on 2013-07-29 (1104 days ago)
InstallationMedia: Xubuntu 13.04 "Raring Ringtail" - Release amd64 (20130423.1)
SourcePackage: lightdm
UpgradeStatus: Upgraded to xenial on 2016-07-30 (6 days ago)

Revision history for this message
Alexis Scheuer (alexis-scheuer) wrote :
Revision history for this message
Alexis Scheuer (alexis-scheuer) wrote :

Hello.

There has been a few changes (even though I don't know which update solved these problems): about this bug, the main change is that the laptop doesn't turn to sleep anymore when I undock it.

I however still have the main problem. I can add that everything is OK after the first login: if I disconnect, the greeter is displayed (with bad dimensions - right of the screen is missing).

Revision history for this message
Alexis Scheuer (alexis-scheuer) wrote :

OK, a few additional info: on 4 tries, I had only 1 unexpected sleep, and only 1 display of the greeter (with bad dimensions). Moreover, each time I disconnect and loose the display (black screen with only cursor), the fan starts to work.

I will check whether the load increases (with a top in TTY 1), and which process is on top, and send you the results tomorrow.

Good evening.

Revision history for this message
Alexis Scheuer (alexis-scheuer) wrote :

Hello.

No surprise: the top process is... lightdm-gtk-greeter. But I discovered that it is the case this morning (I will have to check again).

And I found at last an easy turnaround: the screen is refreshed correctly as soon as... I click with the mouse! I did not try before (I did not think it could be so simple).

As a consequence, this bug is minor (as long as the click works - I will come back if it doesn't).

Bye (I hope).

Revision history for this message
Alexis Scheuer (alexis-scheuer) wrote :

Here come the news for today: the greeter's aspect changed, showing two resolutions (my external and laptop screens do not have the same proportions) displayed on screen (as it did with 14.04, the background is displayed twice on the larger - external - screen, with both proportions), while it was only displayed once since the upgrade.

The problem is that, once I clicked to get the display, I was unable to write on the login pop-up: I could select a region (by a left double click) in the login box, but typing on the keyboard had no effect!..

I started to click here and there, hopping to solve the problem, and succeeded: I had to click on the top bar (with date, language and accessibility selections, ...) to get back to only one display of the background, and be able to type the login and password again.

I hope my story would help, either by the turnarounds if someone else get a similar problem, or to locate the bug(s) and solve it (them).

Robert Ancell (robert-ancell)
affects: lightdm (Ubuntu) → unity-greeter (Ubuntu)
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