I've accidentally checked the CW checkbox on one of my answers (yes, I'm a fool). Since I cannot undo, the solution seems to be to re-post, but this can be quite frustrating since you lose all your votes. A nice solution would be for SO to prompt me with an "are you sure?" message before continuing, when SO has been checked.
Update:
This has been bugging me like crazy - I've been trying to re-create this issue, with no luck. Can you even set CW on an answer after it's been updated? I tried tabbing to the CW checkbox, but it's not possible, so we can rule that out as the cause - and I'd say it's practically impossible for me to accidentally click the button.
I think the cause may be that I didn't accidentally check the box, but migrating from SU to SF caused it to become community wiki... but I didn't think that was possible.
So maybe a warning box isn't the answer here... Maybe I've stumbled across found a bug? Or is this by design?
Update 2:
Actually, maybe there should be the following message:
Are you sure you want to edit? After 10 revisions your answer will be community wiki.
I just realised that's why my answer became CW. Quite annoying.