kupfer inhibits log out/shutdown in Unity

[Rob Allen]

I noticed that log out/shutdown in Unity under Ubuntu 12.04 always shows the "A program is still running..." dialog, with an "Unknown" program that's "Not responding". By a process of elimination I tracked it back to Kupfer: when Kupfer is running, the dialog is shown, but when Kupfer isn't running, the log out/shut down proceeds as I'd expect.

Expected behaviour: Log out/shutdown proceeds normally.
Actual behaviour: Log out/shutdown is blocked, showing the "A program is still running..." dialog.

$ lsb_release -rd
Description: Ubuntu 12.04 LTS
Release: 12.04
$ apt-cache policy kupfer
kupfer:
  Installed: 0+v207-2-oneiric~kupferhopf.gbp5a2be9
  Candidate: 0+v207-2-oneiric~kupferhopf.gbp5a2be9
  Version table:
 *** 0+v207-2-oneiric~kupferhopf.gbp5a2be9 0
        100 /var/lib/dpkg/status
     0+v207-2.precise~kupferhope.gbp199dbb 0
        500 http://ppa.launchpad.net/kupfer-team/ppa/ubuntu/ precise/main i386 Packages
     0+v206+dfsg-1ubuntu1 0
        500 http://gb.archive.ubuntu.com/ubuntu/ precise/universe i386 Packages

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.