Lars, thanks for the thoughtful query. As we have discussed, we developers used to have a fondness for the directness of messages like "SECURITY VIOLATION, THIS INCIDENT HAS BEEN REPORTED", but now we are at the dawn of a new, more cooperative and information age, where think the messages might better be considered in terms of dialogues with intelligent users, including beginners who want to be intermediates and intermediates who want to be advanced. Even better are messages that offer users helpful ways out of the predicaments we would put them in because we have not designed the thing so well the error would not have been made in the first place. So, whatever messages you might put there ought to be trustworthy, loyal, helpful, friendly, courteous, kind, obedient, cheerful, thrifty, and possibly even brave, clean and reverent. As we have discussed, the shortest solution is the best, and so a quick message that gives me options is the best. If the error is known, then a direct instruction towards remedy. If not, an opportunity to survey alternatives, such as a reference to context-dependent help files. I'd think we'd also want to promise hope and deliver on that promise, and for that something like Nima's error message dialogue, where the program's diagnostic error message itself is captured on a form that the otherwise hapless user might add to suggest a nice, warm, fuzzy, cooperative relationship even the most hardened programmer would be challenged not to embrace. In sum, I'd suggest that you think of that message bar as either an opportunity, or poetry, or both.
