is there possible that can multi-protool chatting, like i open a chatroom, then i can invite friends in MSN and in ICQ, they can chat together through my computer? like MSN1 send a message through me to ICQ1, i wish it can be possible, if yes, i hope MIM can be the best messnger~~~

Imposible because the protocols are just too different

It actually is not impossible and there is some messenger out which can do it. The key is to create a "virtual" protocol on top of the existing ones (the aproach could work similar to the metacontacts plugin, which does this already, but only for normal IM sessions).

Of course, this isn't related to the message window at all, it's a plain protocol thing.