I'd like to point out that even if a user goes idle, it might still be a bad time to display notifications. What if a developer is working on a hard problem, an

I'd like to point out that even if a user goes idle, it might still be a bad time to display notifications. What if a developer is working on a hard problem, and pauses for a while to think about the problem, maybe doodle on a whiteboard/paper, etc.? This could actually be the most damaging time to display a distraction to the developer. The solution to this kind of problem would likely need to be slightly different, possibly including simple mechanics such as "Don't bother me during x time" or "Don't bother me for an hour" to give someone that time they need to just focus/think about something for a block of time.