Who remembers the Occam folding editor (1983)? This was the first time I saw this kind of outline-based navigation for code: https://www.transputer.net/tn/03/tn03.html#x1-30002

Don't remember that, but I do remember the one for Gupta SQLWindows. I had a discussion about with its designer on reddit some years back, and he admitted it was a horrible mistake. Programs are text, folding is not a great way to represent text.