“It was called Embrace back then, in 1984, and it came together right after Andy quit Apple (when the Mac was released).

In the Embrace system, user interfaces could operate each other — one window manipulating another as if it were a human user. This might sound like a strange idea, and it was. A hidden digital character — like a figure in a video game that just isn’t animated to appear on-screen — was affixed to the back side of every window. This figure could be trained to operate other windows, each of which had an ability to do the same thing. In this way a whole software environment was made of nothing but user interfaces that could operate each other!”