macOS 12 is officially EOL by Apple and the project only supports
officially supported versions of macOS. Once publicly released, users on
older macOS versions will have to use older released builds.
Fixes#2370
Comparing NSScreens directly was fragile. It appears that AppKit/Cocoa
can return different instances of NSScreen for the same screen for
unknown reasons between calls to windowDidChangeScreen. I don't fully
understand why this happens.
In any case, our comparison was not safe. Instad, we now keep track of
of the CGDirectDisplayID for each screen and compare those instead.