I don't know if this happens on Windows or Linux, i would assume so.
Usualy if the client has some modal window open (login, press ESC to exit, etc) I can hit enter to confirm it.
If I loose connection to the server (Something like "Connection lost, this client will quit now"), this doesnt work. Pressing enter makes the chat-input coming up. This isn't realy useful, since the only thing one can do in this state is to exit. So i think pressing enter here should default to "OK" as in most other windows.
Its a minor thing, but everytime i loose connection, it bugs me again.