Notably, the Apple teams weren't shown the Star, but individually GUI enabled Alto applications, which didn't feature a coherent interface.
Xerox did have a fair chance to monopolising the desktop with the Star (developed by Xerox SDD El Segundo) and was first to market. Also, Apple licensed a lot from Xerox (like the mouse, while they actually came up with their own designs.)
The idea of the "stolen GUI" probably comes from the "Look and Feel" court case, where the argument was irrelevant, as it was found that Apple had unknowingly granted an unlimited license for the desktop GUI to Microsoft. (If the technology had indeed been stolen, would Apple been in any position to grant a license, in the first place? In this sense, the argument is somewhat contrary to its intentions.)
Xerox did have a fair chance to monopolising the desktop with the Star (developed by Xerox SDD El Segundo) and was first to market. Also, Apple licensed a lot from Xerox (like the mouse, while they actually came up with their own designs.)
The idea of the "stolen GUI" probably comes from the "Look and Feel" court case, where the argument was irrelevant, as it was found that Apple had unknowingly granted an unlimited license for the desktop GUI to Microsoft. (If the technology had indeed been stolen, would Apple been in any position to grant a license, in the first place? In this sense, the argument is somewhat contrary to its intentions.)