For several weeks, I haven't been able to go full-screen in any app on my laptop. I thought it was a Chrome problem with YouTube, because when I hit the full-screen button in a movie (bottom-right corner of the movie) it will expand to fill the browser window, but not the whole screen. Then to restore, hitting Escape or the exit-full-screen button doesn't get the video to reduce down again. Reloading the browser page works, though.
However, it's not just a browser problem - I recently discovered that no apps (e.g. Finder, Photos, Terminal, Console) can go full-screen by clicking on the circular green button on the left side of their window bars.
On a random cargo-cult recommendation I saw here, I trashed my
~/Library/Preferences/com.apple.finder.plist file & restarted the Finder, but no differences are observed.
When I hit the green maximize button in a Finder window, it seems to crash that window - I can no longer drag that window around & it doesn't respond to any clicks. Other Finder windows stay fine.
To try to debug, I've poked around in various system logs, but I haven't found anything that looks relevant. Maybe something to do with the WindowServer?
I'm on a MacBook Pro (Retina, 15-inch, Mid 2014), running Sierra 10.12.5.