I think it would be definitely useful to have the Cmd-H shortcut to hide Papers on Mac OS systems (as present in essentially any other Mac app).
Good request. While adding shortcuts, could we have also one for tab-switching?
Papers3 had it, plus a shortcut to return to the Libraray, and another one for editing.
This is a really handy usability feature which is a fundamental feature in window management on Mac, would be great if you could support this.