I have tons of nested headings in Org-mode files, usually collapsed, and I'd like to have a quick look at how many lines are under each of collapsed headings (mostly top-level but sometimes not). Having absolute line numbers displayed sort of works, but then I need to calculate the difference between them. Is there a way to have the number of lines in each fold displayed automatically? Perhaps in the same margin that houses line numbers when they're enabled, or as done by the linum mode?
Having line counts displayed and updated continuously would be perfect—but something that works slowly/one-time would be okay too, since I mostly need this to see which nodes make the file too long, causing Emacs to slow down.
(I've tried to search on the web for this, but search engines all decided that I want relative line numbers instead.)
