Comment 6 for bug 1121854

A workaround solution is execute multiple searches following the same hierarchy of the ToC.

Using the screenshot as example:

seek = document.searchIndexOf("second heading 2", start = 0)
seek = document.searchIndexOf("some heading level 3", start = seek)

I had implemented it some years ago and it require very few changes, it works for me. Unfortunately I was to lazy to learn those "docs vs code check" to submit a patch.

I already get used to the workaround, but I can contribute on this if needed.