This is a list of the API changes detected when comparing the current 0.12 PTR build against the last 1.11.2 live build. Many of the changes are covered in the 1.12 changes sticky post. I've marked those which are incompatible changes to existing functionality with !!!!.
* NEW ClearCursor() - Clears whatever item the cursor is dragging from the cursor.
Once again it appears that Blizzard want to torment us with an API set that we can't actually use, first it was the minigames API, and now this.. My guess by the names is that these are all related to some sort of in-game lottery. Maybe the faire is getting more carnies?
* NEW BuyRandomPicks
* NEW CloseLottery
* NEW GetJackpotAmount
* NEW GetLastLotteryNumbers
* NEW GetLotteryPrizeInfo
* NEW GetMoneyPrizes
* NEW GetNextDrawTime
* NEW GetNumLotteryPrizes
* NEW GetNumPastDrawResults
* NEW GetPastDrawResult
* NEW SubmitNumbers
* NEW HideFriendNameplates() - Hide nameplates above friendly units.
* NEW ShowFriendNameplates - Show nameplates above friendly units.
Music Player (Mac iTunes only)
* NEW MusicPlayer_BackTrack() - Go back a track (Mac iTunes only)
* NEW MusicPlayer_NextTrack() - Go forward a track (Mac iTunes only)
* NEW MusicPlayer_PlayPause() - Toggle play/paulse (Mac iTunes only)
* NEW MusicPlayer_VolumeDown() - Reduce music volume (Mac iTunes only)
* NEW MusicPlayer_VolumeUp() - Increase music volume (Mac iTunes only)
* NEW SendAddonMessage ("prefix", "message" [,"type"]) - Send an inter-addon message to a specific group (type is "RAID" , "PARTY", "BATTLEGROUND", or "GUILD")