
LIGHTBULB (indicator)

When a keyword is Boolean (T/F) and read-only, the interface
interprets it as an indicator light.  By default the light is
a dark red when Off, and a bright glowing red when On.  You
can reconfigure the 'lens colour' of the light if you wish.

A lightbulb can't do anything, only monitor a condition in
the KTL system.  

More intelligent bulbs can monitor alarm or event conditions
(see the Set Alarm popup).

