We should not forget that the original Alto operating system(s) had a GUI already and was the basis of well known applications like Bravo or Gypsy; the original OS and the said applications were implemente in BCPL; and all were operational before Smalltalk-76. By Wirth's first PARC visit in 1976–77, Mesa had already become a self-hosting systems-development tool (small operating system and symbolic debugger); I'm not aware of any substantial Smalltalk influence at that time.
reply> I'm not aware of any substantial Smalltalk influence at that time.
replyYou should be, because I spent hours telling you about it, in detail, with citations from the designers of the Alto and Bravo, less than two weeks ago. At the time you conceded the point and said it was not what you intended to dispute: https://news.ycombinator.com/item?id=49857855