Actually the Demo Center in E40 (I was working for Janet Murray on the Writing Project at the time.) I did eventually end up joining SIPB though.

(And then years later wrote enough of an XOpenDisplay in elisp - by porting the codegen for the perl version to generate elisp - though I never got much further, certainly not far enough for a WM. Amusingly I did find another elisp-X implementation, years later; since elisp doesn't have any native types, your choice of byteorder for the protocol was arbitrary, and we'd chosen opposite ones...)