https://bugzilla.redhat.com/show_bug.cgi?id=683309

Description of problem:
After Qutting launching System preferences in User Menu, g-c-c process is
zombied.
# ps ax | grep defunct
 7259 ?        Z      0:00 [gnome-control-c] <defunct>
 7279 ?        Z      0:00 [gnome-control-c] <defunct>
 7285 ?        Z      0:00 [gnome-control-c] <defunct>
 7394 ?        Z      0:00 [gnome-control-c] <defunct>

$ tail -f .xsession-errors
Window manager warning: Log level 8: _gather_pid_callback: assertion `data !=
NULL' failed
Window manager warning: Log level 8: _gather_pid_callback: assertion `data !=
NULL' failed
Window manager warning: Log level 8: _gather_pid_callback: assertion `data !=
NULL' failed
Window manager warning: Log level 8: _gather_pid_callback: assertion `data !=
NULL' failed

Version-Release number of selected component (if applicable):
2.91.91-1.fc15

How reproducible:
always.

Steps to Reproduce:
1. Click Uer Menu
2. Click System Preferences...
3. Quit System Prefereces (gnome-control-center)


mutter-2.91.91-1.fc15.x86_64
gnome-shell-2.91.91-1.fc15.x86_64
control-center-2.91.91-1.fc15.x86_64