I can completely agree with 15 minutes. As I've said, this just seems to be an annoying thing people are doing that takes away from those wishing to play.

I actually heard a person defend people for AFK'ing for hours at a time because it's just "what they do", but that really isn't a good reason to AFK for hours on end if you aren't playing.

Also I think locking the house doesn't work to boot them... you directly have to go to a GM and have them removed from the house that way. So a way to remove them from the house yourself would also be a nice feature.