Apple didn't "steal" anything because Xerox received a tranche of pre-IPO
Apple shares in exchange for allowing SJ and his folks to visit PARC for a bunch of demos
and do whatever they wanted with what they saw.
Nowadays you can also try out systems like Smalltalk-78, Xerox ViewPoint, etc. as well as
the original Lisa and Macintosh systems in emulation -- and read papers like
"Inventing the Lisa Human Interface," published in ACM Interactions 27 years ago
-- to see just how different what SJ and his people saw at Xerox was from what Apple
shipped in the Lisa and Macintosh 4-5 years after the visit.
- The top-of-screen menu bar was an Apple invention.
- Atkinson's "region" data structure to allow windows to update when
partially obscured was an Apple invention.
- Open/Save file dialogs were an Apple invention for Macintosh, because with 128KB of RAM
it couldn't run both Finder and an application and thus couldn't use Lisa's
"stationery pad" concept.
I can't believe people still don't have a solid grasp of these things after 40
years of both journalism and academia covering them in rather exhaustive detail.
-- Chris