Speaking of... By 1978 InterLISP had grown up quite a bit and its tree-based editor was quite powerful. It supported several tools like Masterscope and DWIM (Do What I Mean), the likes of which I would not see in text-based editors for almost two decades. It was quite habitable, even though a CLI tool and tree-based. I wrote all the code for my dissertation using that editor on a DEC-20. So much better than even EMACS at the time. The simplicity of S-expressions was critical to its success, IMHO. Extending the editor was simple, too. LISP, you know.