Note that the reproduction noted above will no longer work as I pushed a new version of the image into DockerHub with the fix in comment 2; however, the problem should be easily reproducible by simply installing both xscreensaver and xfce4-screensaver.
Note that the reproduction noted above will no longer work as I pushed a new version of the image into DockerHub with the fix in comment 2; however, the problem should be easily reproducible by simply installing both xscreensaver and xfce4-screensaver.