Englebart's NLS created the first implementation of Windows, and of using a Pointer to access Menus. The only addition made by Xerox PARC was the addition of Icons. NLS had bitmapped WYSIWYG graphics, but did not come up with the idea of using Icons to represent commands, using text based menus instead.
Here is a bit of Alto History for you:
The Alto was first conceptualized in 1972 in a memo written by Butler Lampson, inspired by the On-Line System (NLS) developed by Douglas Engelbart at SRI, and was designed primarily by Chuck Thacker.
is considered to be the ancestor of modern computer-aided drafting (CAD) programs as well as a major breakthrough in the development of computer graphics in general. For example, the Graphic User Interface was derived from the Sketchpad as well as modern object oriented programming. Ivan Sutherland demonstrated with it that computer graphics could be used for both artistic and technical purposes in addition to showing a novel method of human-computer interaction.
Some video of Sketchpad in action is available online. (Jump to the four minute mark.)
Going back still farther, Everyone I've mentioned points back to an article by Vannevar Bush published in 1945 describing an imaginary personal computer called the Memex as a huge inspiration.
The Memex (a portmanteau of "memory" and "index", like Rolodex an earlier index portmanteau common at the time) is the name given by Vannevar Bush to the theoretical proto-hypertext computer system he proposed in his 1945 The Atlantic Monthly article As We May Think. The memex is a device in which an individual compresses and stores all of their books, records, and communications which is then mechanized so that it may be consulted with exceeding speed and flexibility. A document can be given a simple numerical code that allows the user to access it after dialing the number combination. Documents are also able to be edited in real-time. This process makes annotation fast and simple. The memex is an enlarged intimate supplement to one's memory.
To sum things up...
Ivan Sutherland's Sketchpad was inspired by Vannevar Bush's idea of the Memex.
Douglas Engelbart at SRI was inspired by Sutherland's Sketchpad when he created NLS.
Xerox was inspired by NLS when they created Alto.
Apple was inspired by Alto when they created Lisa and Macintosh.
None of these was a direct copy of the other. Learn some history, and STAY OFF MY LAWN!
(BTW - Neither Alto nor Macintosh were written in an object oriented programming language.)