I'm not sure what I did, but for some reason all of a sudden the MATE panel on my LMDE 201204 installation vanished from the screen and would not return with rebooting.
I cast about for mate settings on the system, and discovered that if I gave the command "mate-panel" from the command line, the panel comes back. But it's gone again after rebooting.
Based on that, I added the command "mate-panel" as a "Startup Program" using the "Startup Applications Preferences" tool, and that workaround works perfectly. However, I'd prefer to repair the problem at its source.
Suggestions? Thanks!


