I just edited that Wikipedia article. Interlisp on Xerox Daybreaks (and maybe Viewpoint; I've only used Interlisp) had left/middle-click context menus under cur

I just edited that Wikipedia article. Interlisp on Xerox Daybreaks (and maybe Viewpoint; I've only used Interlisp) had left/middle-click context menus under cursor in the mid-1980s, so I imagine it was present on the earlier D* Xerox systems and maybe the Star. Definitely predates Nextstep though.