But- as was so notably pointed out by matthew, the actual technical explanation for the functionality is "weak" so i won't bother either of you with the need to learn why...

Robert, sorry if my post offended you but I'm sure that prior to 1.2 the dome light was working with engines off when the APU was on or external power was connected. Now in 1.2 the dome light doesn't work unless the engines are turned on.Surely this is just a bug that has been introduced in 1.2? Prior to 1.2 it was nice to sit in the VC at night with the dome light on (APU on) whilst setting up the FMC etc prior to pushback/engine start. Now in 1.2 we have to sit in the dark.edit: From reading other posts it must have been 1.0 where it was working... and stopped working in 1.1... i cant remember, i know that it was working at some stage

Peter-Okay- <hatchet buried>.We've been seeing a bit more imperiousness of late- so your post rubbed me the wrong way. The issue here is that we have something to the tune of 30 lights on the MD-11 model. As a result, we have had to use a different method to provide a dome light- and while the dome light on the airplane is powered by the Hot Bat Bus, the effect that we are using is tracking a hard-coded flag within FSX that turns it off when an engine isn't running.We worked around this for the v1.10 update- but this introduced a RAFT of other problems- and we elected to put it back. Sometimes- the original method really was the best idea...