Today when I turned on my computer running Ubuntu 20.04, Mate 1.24.0, I encountered very curious behavior. The top panel contains Application Places System and various program launchers. None of these respond to a mouse click, neither left nor right. However the icons on the right of the top panel (network connections, speakers, calendar) work just fine.
I could not lauch Thunderbird, Firefox, nor anything in the left of the top panel. Placing the mouse in the middle of the screen and right clicking, I got a popup menu which allowed me to launch a terminal. Using this mechanism, I could launch Thunderbird and Firefox, and they seem to work fine.
However, the bottom panel, which usually shows what apps are open, shows nothing. When I click the Show Desktop button at the far left of the bottom panel, all visible windows disappear. Another click and they reappear. But, if I click the Minimize button in an open window, it disappears and cannot be brought back.
It is very awkward trying to work in this situation. Any help is greatly appreciated.
