It must be noted that all the old 'owner-related' features in mIRC where only working for some servers (IRCX).
As of 7.38 (unsure when this was introduced), the 2 events on owner and on deowner are working on unrealircd servers even though these servers are not using any prefix for it (example, irc.swiftirc.net).
@Khaled: is this a bug or on purpose? If it's on purpose, I think it would be fair to add $nick().owner, $nick(,q) and the isowner operator for conditions as well. It would of course make sense to add the 'admin' events, isadmin operator etc (mode +a) too, which, by the way, has been suggested multiple times in the past.