"In 1973, the first graphical user interface was built at PARC, using the desktop as a metaphor. The UI introduced windows, icons, menus, file management, and tool palettes. Looking back at the first screenshots of this first GUI, the designs feel familiar even now. In 1974 PARC developed a What–You–See–Is–What–You–Get cut & paste interface, and in 1975 the demonstrated pop–up menus. The desktop concept was pushed quite a bit further by 1981 in the commercial Xerox Star PC interface, which was an important influence for the PC UI's created at Microsoft, Apple, NeXT, and Sun Microsystems in the 80's and 90's."
(Mike Kruzeniski, 17 February 2011)
