I have browsed around here and googled for over an hour, but are no closer to a solution, so here goes.
lets start by killing
I then do
notify-send "foo" and it reappears, but nothing shows.
Kill it again, but then change volume or brightness, and it reappears and the notification shows.
I have also tried using the python pynotify library, and the
DISPLAY=:0 trick, just in case, but it makes no difference.
I have verified that notification-daemon is not istalled, and reinstalled libnotify-bin and libnotify4. The output of
dpkg -l | grep -i notify is
gir1.2-notify-0.7 libnotify-bin libnotify4:amd64 notify-osd notify-osd-icons python-notify
This is on a fairly fresh install of 14.04, no particular mods.
I have no idea what to try next.
If you do, please speak up! :-)
I see that I was not clear about this when I posted this question, but this is an intermittent problem. Notifications stops or starts working seemingly of it's own. I have not been able to perceive a pattern to it. None of the obvious.
I tried all the standard purging and reinstalling procedures but that made no difference.
I have a tiny suspicion that my video setup might have something to do with this, as I have an Nvidia optimus card that I have not been able to set up quite to my satisfaction despite trying rather hard. Perhaps if some compositing "eye candy" feature is used and that feature is not dependable, that may explain the behaviour I'm seeing.