2 machines with Ubuntu Mate 16.04, with nearly identical features.
On one of them the icons of running apps/programs suddenly don't appear in the panel any more. Just gone.
If I minimize something, it's gone - nowhere to be found. It's still running but I can't find it again.
An internet search didn't turn up anything even similar. Any ideas?
(Opps, found this other question after I posted - my post should go there maybe - how?)
EUREKA!
Found out what it was. In Mate Tweak I had somehow turned off “Enable Indicators” in the Interface section.
The clues were from a post and picture that had a “Panel” section in Mate Tweak - my install doesn’t, the panel options are inside the Interface.
I read your post, I was ok, but after opening Mate
Tweak myself I recognised that the “Allow indicators” option is greyed out at me! A moment later cold icy wind blew my room’s windows in! Then I just felt adrenaline going through my veins like yesterday when I hit Doddy B’s last teeth out at the country fair because Mate is the best DE and my senses haven’t lie so far. Speaking of taking this event into account, what is happening with people’s indicators? No question it’s time to stop this evil which is disturbing our mate indicators. I reinstalled the firewall but no one knows where it came from. It is hiding for sure like dogpoop in tall grass. This problem is very strange. It can come back if it’s root is not pulled out.
I see I forgot part -
when you get the panel back, try adding the Dock applet to it, then your open programs should show.
Was just having this same exact thing happen. Also had to fiddle with tons of ■■■■ to figure out how to get my audio to work. I’m running 17.04
Perhaps it’s about hitting “remove from panel” instead of “move” without realizing I was sitting on the “Dock” or “Notification” applet. 