How is this idea? I just got a brain storm. In chat when we are typing something for a reply.. suddenly we get some message from the other side which needs a different reply. so we cut the text, hold it in clib board.. type another text and then we paste the older one. i bet u do that many times in chat. if there are two areas to type text and when we press enter the current one goes up and another things remains for editing. lets send this suggestion to google!
The number of times you'd want to change your reply is miniscule compared to the number of times you just want the message to be delivered on pressing <enter>
If I were to engineer the same, I would have used the UP/DOWN keys to get the history list of the Chat messages for further edit and send. What say?