Final answer:
Douglas Engelbart invented the computer mouse and demonstrated foundational computer technologies in 1968 during a pivotal presentation known as 'the mother of all demos'.
Step-by-step explanation:
The visionary who invented the computer mouse and showcased revolutionary technology concepts such as windows, email, and live network videoconferencing during "the mother of all demos" in 1968 was Douglas Engelbart. His work marked a significant milestone in the history of computing and paved the way for the graphical user interfaces that we commonly see today. This event was truly a leap forward in technology, demonstrating functionality that wouldn't become commonplace until decades later.