Action Button now a Mixin in 9.0 latest builds

[Xrystal]

nUI uses HookSecureFunc() to hook into alot of Wows ActionButton code. It appears it is all Mixins in 9.0.

For example:
--function ActionButton_Update(self)
function ActionBarActionButtonMixin:Update()

Would I use the Mixin(addonFrame, BlizzardMixin) function to apply the appropriate Mixin to nUI's frames that replace Blizzards ?