I don't think the unsubscribe works with anonymous methods. Also, the event trap reposition is a UI event, so should definitely be in a ScheduledTask, as doing it every time would be insanely expensive. Perhaps you can just set a boolean and do the reposition inside the resetWindowSelection method? This is seems like related behaviour. Then you can simply subscribe processUpdates.trigger to this.

Also, for subscribing to an individual cursor's own moved event, you can subscribe directly to the cursor now rather than going via the document.