“Wasn’t the mouse already invented in 1968?”
A prototype had been made, but it wasn’t patented until 1970. So if you go by the patent date, the answer is no.
Aren't inventing and getting a patent two different thigs? Ask the guy who invented the telephone that Bell stole the workable design from.
mouse
In computing, an input device used to control a pointer on a computer screen. It is a feature of graphical user interface (GUI) systems. The mouse is about the size of a pack of playing cards, is connected to the computer by a wire or infrared link, and incorporates one or more buttons that can be pressed. Moving the mouse across a flat surface causes a corresponding movement of the pointer. In this way, the operator can manipulate objects on the screen and make menu selections.
The mouse was invented in 1963 at the Stanford Research Institute, USA, by Douglas Engelbart, and developed by the Xerox Corporation in the 1970s. The first was made of wood; the Microsoft mouse was introduced in 1983, and the Apple Macintosh mouse in 1984. Mice work either mechanically (with electrical contacts to sense the movement in two planes of a ball on a level surface), or optically (photocells detecting movement by recording light reflected from a grid on which the mouse is moved). Many modern laptops incorporate a Glide Pad, just below the keyboard, which performs the same function.
Most GUIs provide alternative keystrokes for disabled users and these are also useful in emergencies when a mouse fails, or its drivers are deleted or corrupted. Many professional typists use these to avoid the time wasted in moving a hand from the keyboard to the mouse and back again.
In what has come to be known as the mother of all demos Douglas Engelbart demonstrated the first computer mouse at the Fall Joint Computer Expo in San Francisco on December 9, 1968. Engelbart also demoed the chord keyset (on left) that was a keyboard used with five piano-like keys. Englebert worked at the Stanford Research Institute which was also perfecting the acoustic modem at this time. Other technologies demonstrated during the landmark 90 minute session included hypertext, object addressing, dynamic file linking, and shared-screen collaboration in which two persons at different sites communicated over a network via both audio and video.
From http://www.cedmagic.com/history/first-computer-mouse.html