Bug#943543: xfce4-screensaver: Black screen after unlock

[Christoph Groth <christoph@grothesque.org>]

Package: xfce4-screensaver
Version: 0.1.8-1
Severity: important

Dear Maintainer,

I upgraded to Xfce 4.14 from Debian bullseye.  This involved xfce4-screensaver
from unstable.  (I'm actually unsure why it got installed.  I have unstable in
the APT-sources, but APT::Default-Release is set to "testing".)

The screensaver is set to "blank screen".  When unlocking after a system
suspend or simple screen lock, first the unlock dialog is shown normally, but
then, at least sometimes, the screen remains black.  The mouse pointer is
still visible, so this is not a problem of mode setting.  The only way that I
have found to return to a usable system is switching to a text console and
killing xfce4-session.

While I observe this problem sometimes after a very short lock, it occurs
reliably after a long lock.  Curiously, however, I could only ever observe it
when using the built-in monitor of my laptop computer or one external monitor.
With the two external monitors that I connect at work, I never saw it.

As a workaround, I uninstalled xfce4-screensaver and installed "good old"
xscreensaver instead.

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.3.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_DK.utf8, LC_CTYPE=en_DK.utf8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages xfce4-screensaver depends on:
ii  libc6               2.29-2
ii  libcairo2           1.16.0-4
ii  libdbus-1-3         1.12.16-2
ii  libdbus-glib-1-2    0.110-4
ii  libgarcon-1-0       0.6.4-1
ii  libgdk-pixbuf2.0-0  2.40.0+dfsg-1
ii  libgl1              1.1.0-1+b1
ii  libglib2.0-0        2.62.1-1
ii  libgtk-3-0          3.24.12-1
ii  libpam0g            1.3.1-5
ii  libpango-1.0-0      1.42.4-7
ii  libsystemd0         242-7
ii  libwnck-3-0         3.32.0-1
ii  libx11-6            2:1.6.8-1
ii  libxext6            2:1.3.3-1+b2
ii  libxfce4ui-2-0      4.14.1-1+b1
ii  libxfconf-0-3       4.14.1-1
ii  libxklavier16       5.4-4
ii  libxss1             1:1.2.3-1

Versions of packages xfce4-screensaver recommends:
ii  gir1.2-glib-2.0  1.62.0-2
ii  gir1.2-gtk-3.0   3.24.12-1
ii  python3          3.7.5-1
ii  python3-gi       3.34.0-1
ii  xfconf           4.14.1-1

xfce4-screensaver suggests no packages.