Comment 87 for bug 978333

I think I have a reproducible test case:

* log in
* xfce loads panel, begins to restore session, loads firefox etc.
* while this is happening, click on shutdown action button in panel
* click on shutdown again
* Get dialog popup ("Failed to receive a reply from the session manager. Session manager must be in idle state when requesting a shutdown.")
* ctrl-alt-f1 (we somehow broke shutdown, and sometimes it stops and sometimes the system still shuts down, switching to the console seems to prevent consolekit from shutting down)

The system will now be in a state where there is a zombie xfce4-session process, and most other xfce processes that would normally be running (the ones with --sm-client-id in the args) are not running (including xfwm4)

However, there is a new xfce4-session process, and (this is a guess) perhaps it is now responsible for removing xfwm4 from the session.