Best editor for text with folding and hyperlinks?
 

In Windows, there is a NotepadPro text editor. It allows to create document files with mark-up that allows it to display individual parts of a document as if they are separate documents: there is a list of sections in a side panel and an editing panel that shows only the section that is currently selected in the side panel. I see that as the extreme case of folding.

NotepadPro also allows to add mark-up that references sections or individual lines (or other files, etc., but that is a bit less useful). These mark-up works exactly like HTML hyperlinks.

This is very useful when making related notes on one subject: all notes are in one file but can be seen individually and be hyperlinked. NotepadPro is not ideal since sections can be presented as a tree with exactly one level. If it were possible to organize sections as a normal tree it would be much better.

Is there any Linux application with similar or better functions?

As I don't know of any Linux tool with those features, I'll do a suggestion, even though it doesn't have all the listed features: Geany.

Yves.

It looks like Geany makes users happy and they blog good about it. I will have a closer look on it, thanks for the point.

A look on Geany also opened a whole new area to search: a light programmer's editor may replace NotepadPro perfectly if it has good 1) folding on a function level, 2) "Go to definition" function, and 3) ability to easily define what function definition and function calls are, that is, add custom file type. And 4) function list in a side bar will be a plus.