[IBM] 1. Apparently random flashing streaks on the face of
3278-9 terminals while a new symbol set is being downloaded.
This hardware bug was left deliberately unfixed, as some
genius within IBM suggested it would let the user know that
"something is happening". That, it certainly does. Later
microprocessor-driven IBM colour graphics displays were
actually *programmed* to produce green lightning!
2. [proposed] Any bug perverted into an alleged feature by
adroit rationalisation or marketing. "Motorola calls the CISC
cruft in the 88000 architecture "compatibility logic", but I
call it green lightning". See also
feature.