I'm think Engelbart's "Mother of all demos" included folding headings. https://en.wikipedia.org/wiki/The_Mother_of_All_Demos https://en.wikipedia.org/wiki/The_M

I'm think Engelbart's "Mother of all demos" included folding headings. https://en.wikipedia.org/wiki/The_Mother_of_All_Demos https://en.wikipedia.org/wiki/The_Mother_of_All_Demos I think the first "popular" ones were made by Dave Winer (http://davewiner.com http://davewiner.com). Here's a list of some (http://outliners.scripting.com http://outliners.scripting.com)