Bug#1114781: gdm3: Login screen misplaced after resuming from suspend

[Matheus Polkorny]

Package: gdm3
Version: 48.0-3
Severity: normal

Dear Maintainer,

I am experiencing an issue on my Lenovo Neo 50s desktop. When the system
enters suspend mode and the monitor turns off, the monitor wakes up
again after a few seconds.

The login screen (gdm) then appears, but it is displayed incorrectly,
shifted to the top-left corner of the screen. The screen is not lost; I
can interact with it. The display position is corrected as soon as I
click anywhere on the screen, and the login window snaps back to the
center.

Steps to reproduce:
1. Put the system into suspend mode (e.g., via the GNOME menu).
2. The screen goes black.
3. After a few seconds, the monitor powers on by itself.
4. The GDM login screen is shown, but its position is incorrect and
offset to the top-left of the display.
5. Clicking on the screen fixes the position and returns the login
window to the center.

I suspect this might be related to how gdm3 handles display states after
a resume from suspend, possibly failing to position the window correctly
on the first attempt. This behavior happens consistently on my machine.

Thank you for your time and help

-- System Information:
Debian Release: forky/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 6.16.3+deb14-amd64 (SMP w/16 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gdm3 depends on:
ii  accountsservice                             23.13.9-7
ii  dbus [default-dbus-system-bus]              1.16.2-2
ii  dbus-bin                                    1.16.2-2
ii  dbus-daemon                                 1.16.2-2
ii  dconf-cli                                   0.40.0-5
ii  dconf-gsettings-backend                     0.40.0-5
ii  debconf [debconf-2.0]                       1.5.91
ii  gir1.2-gdm-1.0                              48.0-3
ii  gnome-console [x-terminal-emulator]         48.0.1-2+b1
ii  gnome-session [x-session-manager]           48.0-1
ii  gnome-session-bin                           48.0-1
ii  gnome-session-common                        48.0-1
ii  gnome-session-xsession [x-session-manager]  48.0-1
ii  gnome-settings-daemon                       48.1-2
ii  gnome-shell                                 48.4-1
ii  gsettings-desktop-schemas                   49~beta-1
ii  libaccountsservice0                         23.13.9-7
ii  libaudit1                                   1:4.0.5-1
ii  libc6                                       2.41-12
ii  libgdk-pixbuf-2.0-0                         2.42.12+dfsg-5
ii  libgdm1                                     48.0-3
ii  libglib2.0-0t64                             2.84.4-3
ii  libglib2.0-bin                              2.84.4-3
ii  libgtk-3-0t64                               3.24.50-2
ii  libgudev-1.0-0                              238-6
ii  libjson-glib-1.0-0                          1.10.6+ds-3
ii  libkeyutils1                                1.6.3-6
ii  libpam-modules                              1.7.0-5
ii  libpam-runtime                              1.7.0-5
ii  libpam-systemd [logind]                     258~rc3-1
ii  libpam0g                                    1.7.0-5
ii  librsvg2-common                             2.60.0+dfsg-1+b1
ii  libselinux1                                 3.8.1-1
ii  libsystemd0                                 258~rc3-1
ii  libx11-6                                    2:1.8.12-1
ii  libxau6                                     1:1.0.11-1
ii  libxcb1                                     1.17.0-2+b1
ii  libxdmcp6                                   1:1.1.5-1
ii  mlterm [x-terminal-emulator]                3.9.3-3.1
ii  polkitd                                     126-2
ii  procps                                      2:4.0.4-9
ii  systemd [systemd-sysusers]                  258~rc3-1
ii  systemd-sysv                                258~rc3-1
ii  tilix [x-terminal-emulator]                 1.9.6-3
ii  ucf                                         3.0052
ii  x11-common                                  1:7.7+24
ii  x11-xserver-utils                           7.7+11
ii  xterm [x-terminal-emulator]                 398-1

Versions of packages gdm3 recommends:
ii  at-spi2-core                                2.57.1-1
ii  desktop-base                                14.0.0~pre2
ii  gnome-session [x-session-manager]           48.0-1
ii  gnome-session-xsession [x-session-manager]  48.0-1
ii  x11-xkb-utils                               7.7+9
ii  xserver-xephyr                              2:21.1.16-1.3
ii  xserver-xorg                                1:7.7+24
ii  zenity                                      4.1.99-1

Versions of packages gdm3 suggests:
pn  libpam-fprintd        <none>
ii  libpam-gnome-keyring  48.0-3
pn  libpam-pkcs11         <none>
pn  libpam-sss            <none>
ii  orca                  48.1-2

-- debconf information excluded