ReadTheOrg: How does one increase the depth of Table Of Contents

[Anton Latukha]

First, thank you for such marvelous contribution into the community.

I searched a bit around, before asking.

Having a pretty extensive org-file that goes number of heading levels in depth.

How to increase the number of included levels shown in the TOC panel.

I have
Emacs: (setq org-export-headline-levels 4)
Org:

#+OPTIONS: H:4
#+OPTIONS: num:4
#+OPTIONS: toc:4

How to increase the number of levels shown in TOC?

File is here: https://github.com/Anton-Latukha/haskell-notes.
HTML view is here: https://blog.latukha.com/haskell-notes.html

#+HTML_HEAD: <style type="text/css">div.MathJax_Display{display: inline-block !important; width: auto;}</style>

[Anton Latukha]

I still look at the source code from time to time trying to understand how to extend the depth of TOC. But as person that is not familiar with the code - I get too many leads (things that may be or may not related to it), when I try to figure-out how to do it.

I am not asking to get that into the code, some lead would be enough, and I can live with maintaining patches.