I fumbled and clicked around for a while, but I still don't have the slightest idea of what I'm looking at and how to use it. Except for the obvious "an ancient operating system emulated in Javascript."
Click-and-hold the right mouse button on the desktop, and select 'Open a Browser' from the lovely ornate dropdown menu. You'll see a miller column browser at the top of the window.
I came across it the other day in a vid o form 1990 about Lotus Inprov rubbing on NextSTEP. The Wikipedia page mentions it was used by Next, but I also find it interesting that I saw it there just a few days ago :)
