Comment by JdeBP

It's [Alt]+[F4] because before being translated to a GUI setting where [Alt] modifiers denoted things that were the same across all applications, or at least 'system key' events, it was actually plain [F4] to 'save and exit'. This was notably the case in some PC-DOS text editors.

Common User Access (CUA) in 1987 came from the world of IBM mainframes to IBM-involved microcomputer operating systems like PC-DOS and OS/2, and was the idea that there would be a common set of function keys across all 'panels' in Systems Application Architecture (SAA) applications.

Fun fact: CUA didn't originally define [F4] with its current meaning, and it was actually [F3] to exit, after [F1] for help and [F2] for toggling between two sets of function key bindings. But notice how [F5] was refresh all along.

* https://web.archive.org/web/20001117223900/http://publib.bou...

* https://web.archive.org/web/20001102070751/http://publib.bou...