Conversations, character encoding

Unfortunately the way how the conversations work isn't very good. Change of the subject in reply is enough to break whole thread. I think this should be done another way - maybe Gmail should use messages' id? When you are corresponding internationally you will get different default reply subjects and it can make a lots of trouble. BTW: Gmail encodes outgoing messages in UTF-8 format, so when your email client do not support it you are in trouble. But what is Thunderbird for? :).