[iachimoe]

As the article shows, the close button on MacOS classic was basically an empty box, but on mousing down on that box, it transformed into something that looks a bit like an x. I'm basing this on what I can see from using [1], but from my possibly inaccurate recollection of using the real thing in the 80s and 90s, some versions of MacOS had an even more "x like" mouse down image on the close button.

[1] http://jamesfriend.com.au/pce-js/

[lstamour]

Yeah, I was remembering this too. Of course, it also kind of felt like you'd "selected" the box. In fact, I think early checkboxes had x in them on Mac, didn't they? So it might have been a bit of a coincidence ... or an inspiration.

[macrael]

Yeah, weird. I remembered it being just an X but it had lines in all directions.