Currently, WM_ENDSESSION just calls GiveUp() to set the DE_TERMINATE flag. But
for the X server to exit cleanly, we also need the X server dispatch loop to be
unblocked so it can notice that DE_TERMINATE has been set and exit, removing
it's lock file and any unix domain socket.
It appears that the system will terminate the process when the last UI thread in
that process returns from processing WM_ENDSESSION for the last top-level
window.
Since WM_ENDSESSION appears to sent by the system via SendMessage()
(synchronously) and the wndproc is called to process it in the message thread
for that window (the X server thread), we can't easily terminate the X server
dispatch loop from inside the WM_ENDSESSION message processing.
So, create a messaging window, a hidden, top-level window, with a separate
thread to catch this message, and process it by calling GiveUp() and then
blocking on a mutex until the X server dispatch loop exits.
Also, notice when this is a shutdown cancel WM_ENDSESSION message and take no
action.
Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>
