[Someone]

The Apple Lisa was released in January 1983, GEM was first demoed in November 1984 (http://en.wikipedia.org/wiki/Graphical_Environment_Manager, http://en.wikipedia.org/wiki/COMDEX), and Amiga Workbench was released in july 1985 (http://en.wikipedia.org/wiki/Workbench_(AmigaOS), http://en.wikipedia.org/wiki/Amiga_1000)

I don't think anybody ever claimed parallel inventions here.