I would actually expect AR displays to be naturally transparent. I'm not a specialist at all, but achieving a transparent screen with perfectly opaque rendered areas sounds quite unrealistic.
If the display is naturally transparent, I don't see the need for a non-opaque UI.
> If the display is naturally transparent, I don't see the need for a non-opaque UI.
You're right, but it depends on the screen type. It turns out that just being transparent isn't actually good enough, you really want to be able to dim the background as well. This means that you can overwrite the real-world object much more effectively.
If the display is naturally transparent, I don't see the need for a non-opaque UI.