After about 10 minutes of programming, the Auto Respond default message is now editable. So that's one more thing off of that to-do list I posted a few hours ago.
The default message is not just something that is clickable in the message list. It is also used when the auto respond message on the main screen is emptied. Therefore, if you want to set a new default message, you have two easy ways of getting to that message as well. (Hopefully 3 when I get widgets working)
This feature has not been released yet. I want to make a few more changes/addition before releasing a new version.