Currently Aura opens messages in the full Gmail interface. I’ve had many requests for this to be changed to the message only view.
I’ve been thinking about this and can’t see any downsides, especially as most users will probably have their full inbox open already in a pinned tab. It’s also easy to get back to the full inbox from this view if needed.
It’s a small change, and pending any big objections I’m making this part of version 5.