Consider this question as specific example: iPad keyboard will not dismiss if modal ViewController presentation style is UIModalPresentationFormSheet
The answer that is currently accepted was indeed the correct answer when the question was asked. But with recent software updates (iOS 4.0 in particular), the answer has now changed. I don't like to switch my accepted answer because this would cause whoever originally answered to insta-lose 15 rep.
How should we deal with a situation like this?
What if an "old" question with a new answer could switch the accepted answer to that new answer, giving the new answer something like 5 rep, but leaving the 15 rep with the old answer (maybe marking it as "previous answer" or something)?