Screenshot 1: new proposal
Screenshot 2: highlighting changes
Screenshot 3: current situation
I opened a wishlist entry (feature request) at http://bugs.kde.org/show_bug.cgi?id=122310
So if you care, vote for it!
When you always (or often) use GPG encryption, it gets annoying by time, how incoming and outgoing messages are formated. Of course it is important, that encrypted and unencrypted messages can be easily visually distinguished, but the "incoming encrypted message:" and "outgoing encrypted message:" text that is displayed ahead of every messages is to much visual overhead by time. So it would be nice if this was more decent or could be configured by the user. Best would be if the display of encrypted messages in chat window could be setup by XSL-Styles, so style designers could integrate encrypted messages nicely with the rest of their style.
Furthermore, you should be more easily able to recognize if a message you are going send and which is currently typed in respectively, will be encrypted or not. Just indicating "outgoing encrypted message:" (current situation) after the message was sent can be too late in some cases.
Best would be if the message input area could be customized by XSL-styles, too (like the chat window). Well, there should be different states or classes for the message input area (at least encryption on / encryption off) so that different formatings could be applied by the style.
Finally, since there is enough toolbar space left, it would be nice if one could add an encryption button to the main toolbar for faster encryption on/off switching (like Kmail has).