With Facebook's F8 developer event approaching, word has spread that more users can try its "downvote" button on post comments. While it's not the fabled "dislike" button that some would like to see, it is a way for users to flag comments Reddit-style on public posts. That may come in handy as it rolls out more video, VR and whatever else' we'll hear about during its 1 PM ET keynote. Facebook confirmed to CNET that its test is occurring in New Zealand, but many users in Australia report seeing the buttons too.