Do you mean to tell me that there are editors that do not have this feature?

Some of us have been doing this long enough that 'new fangled tools' can be hard to keep up with. I "just looked" for a decent code collapsing editor "a few years ago". ;) At the time, I was disappointed with that new IDE, Eclipse. It was hard to install, was Java-centric, didn't have decent Perl support, and was too much trouble for small scripts. ;) (1)

I just gave the folding option for vim a try. I'll pass on that particular implementation of folding: It doesn't qualify as 'good' (or at least I couldn't figure out how to collapse/uncollapse stuff any other way than changing the 'foldlevel'). The other features in the Perl-Support plugin look very interesting.

Looking at SciTe and Geany (neither of which I had seen before today) I am initially impressed with their implementations of folding. Geany looks nice in general. My desktop work tools may be about to change.

Live and learn.

* 1 Yes. I know. My point was that it has been a few years since then. See the winking smilelies.