I just looked at the folding.el mentioned in that other thread and it mentioned that imenu (included with Emacs) and hideshow might be good packages for function/block-level hiding. The former is interesting, and I didn't know about it, but it doesn't provide hiding capability. I just tried out the latter and it seems good so far at hiding blocks.
Thank you (and above posters)! I'll try out hideshow I think, since it seems to automatically work based on the structure of the code itself and is closest to what I wanted (a toggling widget to the left of each "sub" keyword, etc. I'll see if it also can hide sections i.e. separated by a line leading with two sharps which happens to be an idiom I tend to use, though I guess I should use pod style. Thanks!