Well the question is "is the GUI that people are using today closer to the PARC GUI or closer to the Mac/Lisa GUI?"

The Apple and Lisa groups were unquestionably influenced by PARC, but a lot of the innovations that are used in today's GUIs come from Apple: http://www.folklore.org/StoryView.py?project=Macintosh&s...

Although, important to note that while Xerox invented GUIs, they were about to trash the project before Apple stepped in and nurtured it. Speculation about what would have happened if they didn't do this is mostly meaningless, but disregarding the promulgation and popularization of GUIs in lieu of crediting only their original inventor is totally unfair.

Actually, Xerox invented some important technologies, such as the mouse and the idea of a windowed interface, but this was not the GUI. That was invented by Apple. The xerox interface was more akin to emacs multi-document mode, there was no desktop metaphor, no file/folders organization, no trash can, the menubar was a very different conceptualization, etc.

Xerox categorically did not invent the mouse. Doug Engelbart invented the mouse in the mid-to-late 1960s. See http://www.youtube.com/watch?v=JfIgzSoTMOs for what is described as "The Mother of All Demos". As to the GUI, again PARC then Apple innovated on the original ideas of others. Ivan Sutherland is credited ad really being the first to develop the notion of the "GUI" - again in the late 60s - with Sketchpad http://www.youtube.com/watch?v=mOZqRJzE8xg. The Xerox interface was in fact essentially Smalltalk http://en.wikipedia.org/wiki/Smalltalk and http://homepage3.nifty.com/old_apple_world/photo/SmallTalk21...

I'll admit at the time I posted my comment, I wasn't particularly well versed in the history of computing. Thanks for the links, they are insightful.

I didn't say Apple invented the mouse or the idea of a winding UI, I said Apple invented the GUI and the personal computer.