Login screen appears on only one monitor and it's not the one I want

[Stuart Bishop]

Upstream bugs:
https://gitlab.gnome.org/GNOME/gdm/issues/168
https://gitlab.gnome.org/GNOME/gdm/issues/183
https://gitlab.gnome.org/GNOME/gdm/issues/195
https://gitlab.gnome.org/GNOME/gdm/issues/319
https://gitlab.gnome.org/GNOME/gdm/issues/372
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3867

The Ubuntu login screen is tiled on all displays, not mirrored, making it nearly impossible to login when using an external monitor if the laptop screen is not visible.

There appears to be no available control to alter the display settings of the login screen. Prior to bionic, the controls followed the mouse onto different displays so you could login by giving the mouse a swipe to the right to get the controls to appear.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 3 22:13:53 2018
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1723025, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Stuart Bishop (stub)]

I don't think this is a dupe of Bug #1723025, which is discussing behavior when a screen is disabled such as a laptop being closed while an external monitor is connected. In my case, the laptop screen is not disabled (the laptop is not designed to operate with the lid closed). The laptop screen simply cannot be seen when using the external monitor and keyboard due to its physical positioning.

Ideally, for this bug to be fixed the screens would be mirrored and the login screen displayed on all screens. Fallback would be to implement previous release behavior, where the login controls followed the mouse pointer and would appear on whatever screen the mouse pointer is moved to.

[Daniel van Vugt (vanvugt)]

It's a different project that implemented "login controls followed the mouse".

I know many people would like to see the same in gdm3. It just hasn't been done yet.

Please log a request for the feature here:
  https://bugzilla.gnome.org/enter_bug.cgi?product=gdm
and then let us know its URL.

[Stuart Bishop (stub)]

https://bugzilla.gnome.org/show_bug.cgi?id=794971

[Stuart Bishop (stub)]

Upstream issue shuffled to to https://gitlab.gnome.org/GNOME/gdm/issues/372

[Daniel van Vugt (vanvugt)]

Reworded the bug title because I keep finding duplicates of this issue and it's hard to direct people here while the bug title only describes one possible solution instead of describing the problem. Other people have requested other solutions like honoring their account's own primary monitor preference as a global setting.

In general it's good bug hygiene to describe the problem only.

[Daniel van Vugt (vanvugt)]

That said, I personally agree that mirroring the login screen on all monitors would be best.

[wen efil (bangkokguy)]

I switched to lightdm but the problem still exists: if I attach an external monitor to my laptop, no login screen appears, nevertheless, I can enter my credentials blind, and than everything's fine.
If I boot with nomodeset than at least the login is ok. I've got a dell laptop with integrated intel video.

[Timo Suoranta (tksuoran)]

I have exactly the same issue. This is really annoying bug.

[Timo Suoranta (tksuoran)]

I agree mirroring login screen to all displays is the ideal default behavior.

[Chris Rainey (ckrzen)]

WORKAROUND: replace gdm3 with slick-greeter + lightdm-settings + gnome-screensaver + numlockx(optionally)

Greeter will auto-appear on whichever screen your mouse is on or moves to, dynamically.

See: https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1820423

[Diego (diego-giglio)]

Are there some solution for it?

[Diego (diego-giglio)]

In addition, for me, install lightdm solve the problem. Now, I can see login screen on both monitors :)

[Ponnuvel Palaniyappan (pponnuvel)]

This still happens on Ubuntu 20.04 (Focal), too. In my case, I have one external monitor which is mirrored. But the login screen appears only on the laptop's screen but not on the external monitor's display.

[isaac (isaac-mao)]

same issue here, on Ubuntu 20.04(Focal)

[David Pérez Terol (ter0x)]

Hello!

I am experimenting the described behaviour in Ubuntu 20.04.1

[Daniel van Vugt (vanvugt)]

Moved to gnome-shell. Any graphical aspect of the login screen is implemented in gnome-shell, not gdm.

[Daniel van Vugt (vanvugt)]

WORKAROUND/FIX:

1. Log in and configure your multi-monitor desktop the way you want.

2. sudo cp ~/.config/monitors.xml ~gdm/.config/

3. Edit ~gdm/.config/monitors.xml to make sure the monitor you want as primary is set as <primary>yes</primary>

4. Log out.

[Daniel van Vugt (vanvugt)]

We could add a button to gnome-control-center that does the above. Label the button "Apply on login screen".

[defaria (andrew-defaria)]

The problem with the workaround/fix is that that fix can and will get overwritten by newer versions of GDM3. That just happened to me and I had a hard time figuring out how to fix it until I came across this again...

[Kees Bakker (keestux)]

Another problem with the workaround/fix is that it does NOT work when wayland is enabled for the login screen.

You have to uncomment WaylandEnable=false in /etc/gdm3/custom.conf and then systemctl restart gdm.