gajim ignores nick-change conflict in multi user conversation
when in a group chat you do "change nickname" and fill in an already existing name, you get a server error. so you still hold the same nick. let's say your used to be "bb" but now are "germany666". if you type something, your words aren't blue anymore, they are red. if somebody else (including yourself) says "germany666, hi" then it is highlighted. and if germany666 himself says something, it is blue instead of red. (and if somebody says "bb, hi" it isn't highlighted at all). everything you say has "bb" as author though.
tested in gajim@conference.jabber.no