Richard Hess was working in the years following the AI Winter, doing GUI prototyping with OSF/Motif on Unix workstations. He discovered Niels Mayer's WINTERP project and used it extensively — it was the right tool at the right time. Rather than writing and recompiling C code to build Motif interfaces, WINTERP let him drive widgets interactively through Lisp, dramatically accelerating prototyping.
This fit naturally with how he worked: a heavy Emacs user who did everything — email, coding, exploration — inside the editor. Lisp was his preferred language above all others. WINTERP's own documentation called out Gnu-Emacs as a direct design influence, so the workflow Mayer built for was exactly the one Richard was living.