[akreal]

I also expected screenshots there, especially given the word "interface". Turns out, it's not about user interface (UI), it's about programming interface (kinda API). It allows calling window-related functions on Macintosh, X Window System, and Atari. So the resulting windows were looking like a native UI, I assume.

[robotresearcher]

The readers' natural question is 'does this look reasonable on multiple platforms?'. A two-second glance at two or three screenshots goes a long way to answering that.

[pantulis]

In hindsight, this sounds more reasonable in 2026 where graphical documentation is taken for granted. In those days I think anyone would have spooled the .ps to their nearest laser printer and begin building something quickly with it just to check the looks.

I remember following a "build your own text windowing system" tutorial printed in a hcontinous paper back then

[robotresearcher]

The document looks to be nicely rendered, likely from Postscript. Maybe generated by roff, since it doesn't look like TeX. Screen cap bitmaps could be converted to EPS and inserted into the Postscript.

If it was a PS document, you would have to spool it to a printer or screen renderer to read it anyway. The X Window System debuted in 1984, so on-screen renders would have been not too hard to find in a CS department in 1989.