You've always been able to reply to a message by clicking on the subject line of the message.
Though, since I've changed the defaults of the messages from being displayed in a subject line format to displaying in a nested format, it's not that obvious that clicking the subject line is how to get to reply to them.
So, I've added a nice new icon beside the subject line, which when clicked on brings up the reply form for that message.
Any other feedback on the message system is appreciated.

