Bug#971406: gnome-control-center: cannot set external display only, freezes

[tom]

Package: gnome-control-center
Version: 1:3.30.3-2~deb10u1
Severity: important

Gnome-conrol-center > devices > displays > external monitor set
to primary in 'join displays'> 'single display'
turns off both LVDS and external monitor, freezes keyboard and 
mouse control, hard reboot only solution.

If 'mirror' is used, the external monitor is available, but only at
the resolution of the LVDS or lower. 

I expected it was possible to have just the external monitor, and LVDS 
off.

-- System Information:
Debian Release: 10.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-10-amd64 (SMP w/8 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8) (ignored: LC_ALL set to en_US.utf8), LANGUAGE=en_US.utf8 (charmap=UTF-8) (ignored: LC_ALL set to en_US.utf8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gnome-control-center depends on:
ii  accountsservice            0.6.45-2
ii  apg                        2.2.3.dfsg.1-5
ii  colord                     1.4.3-4
ii  desktop-base               10.0.2
ii  desktop-file-utils         0.23-4
ii  gnome-control-center-data  1:3.30.3-2~deb10u1
ii  gnome-desktop3-data        3.30.2.1-2
ii  gnome-settings-daemon      3.30.2-3
ii  gsettings-desktop-schemas  3.28.1-1
ii  libaccountsservice0        0.6.45-2
ii  libatk1.0-0                2.30.0-2
ii  libc6                      2.28-10
ii  libcairo-gobject2          1.16.0-4
ii  libcairo2                  1.16.0-4
ii  libcanberra-gtk3-0         0.30-7
ii  libcanberra0               0.30-7
ii  libcheese-gtk25            3.31.90-1
ii  libcheese8                 3.31.90-1
ii  libclutter-1.0-0           1.26.2+dfsg-10
ii  libclutter-gtk-1.0-0       1.8.4-4
ii  libcolord-gtk1             0.1.26-2
ii  libcolord2                 1.4.3-4
ii  libcups2                   2.2.10-6+deb10u3
ii  libfontconfig1             2.13.1-2
ii  libgdk-pixbuf2.0-0         2.38.1+dfsg-1
ii  libglib2.0-0               2.58.3-2+deb10u2
ii  libgnome-bluetooth13       3.28.2-4~deb10u1
ii  libgnome-desktop-3-17      3.30.2.1-2
ii  libgoa-1.0-0b              3.30.1-2
ii  libgoa-backend-1.0-1       3.30.1-2
ii  libgrilo-0.3-0             0.3.7-1
ii  libgtk-3-0                 3.24.5-1
ii  libgtop-2.0-11             2.38.0-4
ii  libgudev-1.0-0             232-2
ii  libibus-1.0-5              1.5.19-4+deb10u1
ii  libkrb5-3                  1.17-3
ii  libmm-glib0                1.10.0-1
ii  libnm0                     1.14.6-2+deb10u1
ii  libnma0                    1.8.20-1.1
ii  libpango-1.0-0             1.42.4-8~deb10u1
ii  libpangocairo-1.0-0        1.42.4-8~deb10u1
ii  libpolkit-gobject-1-0      0.105-25
ii  libpulse-mainloop-glib0    12.2-4+deb10u1
ii  libpulse0                  12.2-4+deb10u1
ii  libpwquality1              1.4.0-3
ii  libsecret-1-0              0.18.7-1
ii  libsmbclient               2:4.9.5+dfsg-5+deb10u1
ii  libsoup2.4-1               2.64.2-2
ii  libupower-glib3            0.99.10-1
ii  libwacom2                  0.32-1
ii  libwayland-server0         1.16.0-1
ii  libx11-6                   2:1.6.7-1+deb10u1
ii  libxi6                     2:1.7.9-1
ii  libxml2                    2.9.4+dfsg1-7+b3

Versions of packages gnome-control-center recommends:
ii  cracklib-runtime              2.9.6-2
ii  cups-pk-helper                0.2.6-1+b1
ii  gkbd-capplet                  3.26.1-1
ii  gnome-online-accounts         3.30.1-2
ii  gnome-user-docs               3.30.2-1
ii  gnome-user-share              3.28.0-2
ii  iso-codes                     4.2-1
ii  libcanberra-pulse             0.30-7
ii  libnss-myhostname             241-7~deb10u4
ii  mousetweaks                   3.12.0-5
ii  network-manager-gnome         1.8.20-1.1
ii  policykit-1                   0.105-25
ii  pulseaudio-module-bluetooth   12.2-4+deb10u1
ii  realmd                        0.16.3-2
ii  rygel                         0.36.2-4
ii  rygel-tracker                 0.36.2-4
ii  system-config-printer-common  1.5.11-4

Versions of packages gnome-control-center suggests:
ii  gnome-software           3.30.6-5
ii  gstreamer1.0-pulseaudio  1.14.4-1
pn  libcanberra-gtk-module   <none>
ii  libcanberra-gtk3-module  0.30-7
ii  x11-xserver-utils        7.7+8

-- no debconf information