One of the users of StackExchange asked a question, which at first glance may look weird: why is the mouse cursor slightly tilted and not straight? Indeed, why the cursor is not vertical? The answer was given by an expert, who is familiar with the history of computer hardware. He confirms, that initially the mouse and therefore the mouse cursor invented by Douglas Engelbart, was an arrow pointing up. However, graphical interface for the first operating system in the world was designed by Xerox, precisely — the Palo Alto Research Center.