gnome-screensaver loses screen control when desktop is Flashback + Compiz on single screen computers

[Fredrik Jacobsson]

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
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Description: Ubuntu Xenial Xerus (development branch)
Release: 16.04

I use gnome-flashback with compiz on my machines. I have four (2 single screen and 2 dual screen) and the problem only occur on the single screen machines.

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2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
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gnome-screensaver:
  Installed: 3.6.1-7ubuntu4
  Candidate: 3.6.1-7ubuntu4
  Version table:
 *** 3.6.1-7ubuntu4 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

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3) What you expected to happen
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Get back to desktop when I touch the mouse or keyboard.

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4) What happened instead
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Screen is on and black except the clock line and locked (Why? I do not lock my screens) user name at the top, plus the mouse pointer. (See attached photo)
The only keyboard input available is switch to virtual terminals.
There is no way to get back to the desktop. I just kill the session by "sudo killall lightdm" and log in again.

I have no problems with my dual screen machines or if I log in using Metacity.

The lines that mentions screensaver in syslog:

Jan 25 08:35:40 Tvburk org.gnome.ScreenSaver[1406]: (gnome-screensaver:1532): GLib-CRITICAL **: Source ID 33 was not found when attempting to remove it
Jan 25 21:41:26 Tvburk org.gnome.ScreenSaver[1406]: (gnome-screensaver:1532): GLib-CRITICAL **: Source ID 77 was not found when attempting to remove it
Jan 26 04:30:30 Tvburk org.gnome.ScreenSaver[4193]: ** (gnome-screensaver:4321): WARNING **: Couldn't get presence status: The name org.gnome.SessionManager was not provided by any .service files
Jan 26 04:30:32 Tvburk gnome-session[4277]: ** (gnome-screensaver:4398): WARNING **: screensaver already running in this session
Jan 26 04:30:32 Tvburk gnome-session[4277]: ** (gnome-screensaver:4407): WARNING **: screensaver already running in this session