The model for Glancing is people sitting at work, focused on their own stuff. Every so often, somebody looks up to rest their eyes or because they're thinking, maybe actually to look at someone else. Maybe they catch someone's eye and that person nods back. And then they all get on with their work.
If there's more of that kind of eye contact going on, the eye is more open (or obvious). If there's less, it's smaller.
For work, read any small group situation: a pub or whatever. The software means you don't need to be in the same place.