Bug#867555: gnome-shell: Tries to drive monitor at unsupported refresh rate

[Mark Brown]

Package: gnome-shell
Version: 3.26.1-3
Followup-For: Bug #867555

This bug appears to have become *much* worse on a recent upgrade.  As
well as having once again forgotten my monitor settings I'm now seeing
almost any attempt to change settings away from the default resulting in
at least one of my monitors (generally my 16:9 primary display) being
disabled and there is no longer any visible refresh rate control so the
workaround I was previously using (lowering the refresh rate on the
primary display) is no longer available.

In addition it feels like the UI in the settings daemon has started
doing some kind of snap to grid thing for aligning the displays which
isn't helpful.

I can get things kind of working if I disable monitor 3, leave monitor 1
at the default resolution and leave monitor 2 with the top aligned with
the top of monitor 1 (it physically is much lower) but clearly this is a
substantial regression.  This affects both X11 and Wayland sessions.

My three monitors are:

  1: 2560x1440 DisplayPort
  2: 1280x1024 DVI
  3: 1280x1024 DVI

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.13.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages gnome-shell depends on:
ii  caribou                                      0.4.21-2
ii  dconf-gsettings-backend [gsettings-backend]  0.26.1-1
ii  evolution-data-server                        3.26.1-1
ii  gir1.2-accountsservice-1.0                   0.6.45-1
ii  gir1.2-atspi-2.0                             2.26.0-2
ii  gir1.2-caribou-1.0                           0.4.21-2
ii  gir1.2-freedesktop                           1.54.1-1
ii  gir1.2-gcr-3                                 3.20.0-5.1
ii  gir1.2-gdesktopenums-3.0                     3.24.1-1
ii  gir1.2-gdm-1.0                               3.26.1-3
ii  gir1.2-geoclue-2.0                           2.4.7-1
ii  gir1.2-glib-2.0                              1.54.1-1
ii  gir1.2-gnomebluetooth-1.0                    3.26.1-1
ii  gir1.2-gnomedesktop-3.0                      3.26.1-1
ii  gir1.2-gtk-3.0                               3.22.24-3
ii  gir1.2-gweather-3.0                          3.26.0-1
ii  gir1.2-ibus-1.0                              1.5.14-3
ii  gir1.2-mutter-1                              3.26.1-6
ii  gir1.2-networkmanager-1.0                    1.8.4-4
ii  gir1.2-nmgtk-1.0                             1.8.4-1
ii  gir1.2-pango-1.0                             1.40.12-1
ii  gir1.2-polkit-1.0                            0.105-18
ii  gir1.2-rsvg-2.0                              2.40.18-2
ii  gir1.2-soup-2.4                              2.60.1-1
ii  gir1.2-upowerglib-1.0                        0.99.6-1
ii  gjs                                          1.50.1-2
ii  gnome-backgrounds                            3.26.2-1
ii  gnome-settings-daemon                        3.26.1-2
ii  gnome-shell-common                           3.26.1-3
ii  gsettings-desktop-schemas                    3.24.1-1
ii  libasound2                                   1.1.3-5
ii  libatk-bridge2.0-0                           2.26.0-2
ii  libatk1.0-0                                  2.26.1-1
ii  libc6                                        2.24-17
ii  libcairo2                                    1.15.8-2
ii  libcanberra-gtk3-0                           0.30-3
ii  libcanberra0                                 0.30-3
ii  libcroco3                                    0.6.12-1
ii  libdbus-glib-1-2                             0.108-2
ii  libecal-1.2-19                               3.26.1-1
ii  libedataserver-1.2-22                        3.26.1-1
ii  libgcr-base-3-1                              3.20.0-5.1
ii  libgdk-pixbuf2.0-0                           2.36.11-1
ii  libgirepository-1.0-1                        1.54.1-1
ii  libgjs0g [libgjs0-libmozjs-52-0]             1.50.1-2
ii  libglib2.0-0                                 2.54.2-1
ii  libglib2.0-bin                               2.54.2-1
ii  libgstreamer1.0-0                            1.12.3-1
ii  libgtk-3-0                                   3.22.24-3
ii  libical2                                     2.0.0-0.5+b1
ii  libjson-glib-1.0-0                           1.2.8-1
ii  libmutter-1-0                                3.26.1-6
ii  libnm-glib4                                  1.8.4-4
ii  libnm-util2                                  1.8.4-4
ii  libpango-1.0-0                               1.40.12-1
ii  libpangocairo-1.0-0                          1.40.12-1
ii  libpolkit-agent-1-0                          0.105-18
ii  libpolkit-gobject-1-0                        0.105-18
ii  libpulse-mainloop-glib0                      11.1-1
ii  libpulse0                                    11.1-1
ii  libsecret-1-0                                0.18.5-4
ii  libstartup-notification0                     0.12-4+b2
ii  libsystemd0                                  235-2
ii  libx11-6                                     2:1.6.4-3
ii  libxfixes3                                   1:5.0.3-1
ii  mutter                                       3.26.1-6
ii  python3                                      3.6.3-2

Versions of packages gnome-shell recommends:
ii  chrome-gnome-shell    9-1
ii  gdm3                  3.26.1-3
ii  gkbd-capplet          3.26.0-2
ii  gnome-control-center  1:3.26.1-2
ii  gnome-user-docs       3.26.1.1-1
ii  iio-sensor-proxy      2.2-1
ii  switcheroo-control    1.1-1
ii  unzip                 6.0-21

Versions of packages gnome-shell suggests:
ii  gir1.2-telepathyglib-0.12   0.24.1-1.1
ii  gir1.2-telepathylogger-0.2  0.8.2-2

-- no debconf information