i think the "mock 3d" stuff was ultimately inspired by NextStep (1988), although they did it in a classier way than Windows, Motif, or the Mac (either in the late classic (8 or 9) or OSX)
Yeah I made this same point a few days ago on a similar topic about the use of the win95 style in SerenityOS, etc.
I remember back when NeXTstep was new, really lusting over one, but all I had was my little Atari ST.. and spending many hours writing up pretend 3d relief widgets in GFA Basic on it. We were in love with our colour palettes and the illusions they could give :-)
I loved the NeXT interface for years but it feels stylistically over the top to me now. Love the draggable menus tho.
Another GUI that had 3d relief that I feel did it really nice was Sun's OpenLook style. I used olwm as my window manager for many years. Always preferred that over Motif.
