A little more info on Xerox, because no-one ever seems to get it right.
They developed the graphical interface for their Star workstations with the purpose of making the operating system, file management, networking and email transparent to the operator. Their development environment was called Mesa, which was a lower level interface but graphical none the less. It had an incredible set of development tools for its day, and some smart people at Xerox thought it would make the basis for a great CAD program. They developed Expert, which had three modules - an intuitive 2D drafting program that had intelligent menus - a schematic capture program, and a PCB layout program. All three worked together as a single package in the same environment. If you wanted the Star interface, you had to reboot. We used it for tech pubs.
Versatec, the plotter division of Xerox, was given the task of selling Expert into the engineering world, and they had some success, but not much. Then EIS took it over and underbudgeted it. They tried to kill it off, but the EDGE user group heard about it and there was open warfare between Xerox customers and EIS to keep Expert going. I know this because I led it. But by then Xerox's name in computing was mud, even if their 6085 workstation and their upgrade of Star, now called Viewpoint, was slicker than anything Apple or Msoft could come up with in 1987. All of it, including the operating system, networking, graphical interface and applications took up less than 20 MB!
Xerox had killer software in the 80's. Their management was too busy playing internal politics to notice, and all of it went down the drain. Too bad.