I was analyzing ActionButton.lua and I've found that Blizzard uses something different for handling their action bar cooldowns instead of events (event code is there, but the following code suggests that they rewrote it):
--self:RegisterEvent("ACTIONBAR_UPDATE_COOLDOWN"); not updating cooldown from lua anymore, see SetActionUIButton
I tried to find any information about that function but did not find anything. Is it possible to use this function for my own frames? I understand that I can inherit from ActionButtonTemplate, but there's a lot of stuff there that I don't need so instead of disabling it, I'd prefer just to cut it all. Basically I want to display icon with radial cooldown and nothing else.