After discusing a bit with @halfline:
19:45 anyway that batch stuff needs to die in a fire
19:46 it solved a pressing need years ago for a completely different style of login screen
19:46 it's hardly used now, and the few places where it is used, could just be promises i think
19:46 now that promises are a thing
We decided to remove all this stuff and porting it to use Promise's and (when it was the case) easing transitions.
It required adding some new kind of Promises to be able to easily cancel a promises chain in a shot.
Ideally this can be cleaned up more by mixing it with !1628 (as having transitions as promises can make some cases even nicer).