Summary: keyboard suddenly stops working in all mate-terms
Within the last few months on two different Ubuntu laptops I've been running for years (and upgraded to Ubuntu 18.04 when it was released), I've developed this new problem with mate-terminal: I lose all keyboard interaction. The mouse still works, but no response to any keystrokes to any open terms, or any newly launched terms.
The problem doesn't seem related to anything in particular that I'm doing with the term (sometimes I'm doing nothing, sometimes I'm in vim, sometimes just issuing commands in bash. Killing all the mate-term processes fixes it (killall mate-term) but I'd like to fix the root cause if I can, or alternatively, find a better way to unlock the terms without killing them all.
xterm continues to work fine while mate-term is locked up.