OSX is a wonderful operating system - which is to say, it’s Unix but I can print things and use WiFi properly. I can edit a pdf, etc.
OSX is, in many ways, an absurd operating environment.
If you need any proof of this, just click the little green dot in the upper left of an open window…
It goes full-screen - isn't that an expected outcome?
Not exactly ...
First of all, for most of the life of OSX, clicking the green dot caused the window to resize larger, but not occupy full screen, by some measure I could never discern. That was always braindead.
Second of all, while the current behavior that I see (expand to literally full screen) is sort of an improvement (that is, at least it makes some sense) it's still badly behaved because bringing a window to literally full screen blanks out my other monitors (!@#) ... and now we're drifting into OSX treatment of multi-monitors which is another few layers of hell.
FWIW, IMO, the correct behavior is to maximize the window in the workspace - which is almost identical, but not quite, to the literal screen.
Really? That's not what it does for me. Right at this very moment I have a full screen app running on my MacBook Pro screen and a desktop on my monitor. Do you have "Displays have separate Spaces" turned off in Mission Control preferences?
I rather disbelieve in the idea that these things have "correct" semantics; only "what I am used to". At this point, I'm very used to the way macOS works and I find it considerably more pleasant than other windowing environments. Being able to full screen an app and then multi-swipe left or right between spaces or up for App Exposé is natural to me.
I've no doubt I could unlearn this and learn something else though.
I routinely have mail.app or Firefox fullscreen in one, with emacs or another browser window fullscreen in the other.