In the comment field on StackOverflow (and other StackExchange sites as well, I presume) you're required to write 15 characters for the server to accept your post. If a shorter post is submitted, an information message states that the comment is too short. That is all good.
However, below the comment field is a counter, which counts up to 15 and then down from however many characters you're allowed to type minus fifteen. This counter doesn't always act the same as the actual validation: if I pad my message with whitespace, the validation notices and still says the message is too short, but the counter does not notice, and counts as usual.
Suggested fix: make the character counter trim the message before it counts, so the two messages say the same thing.