Look at this
http://esodata.uesp.net/100011/data/...ForUpdate.html
You'll see a bunch of cases where the game code calls RegisterForUpdate function on a control. I'm only 90% sure of what it does, do you guys know ?
What I got from it is that it registers a callback for when a given UI is updated (more like a tick, and many times per second actually, maybe the same as frames per second) but I'm not sure about the second argument, which looks like a delay. Maybe it's something like, "on update call this, but only once every X milliseconds" ?