I previously submitted a bug on what I thought was a code bug, but which
turned out to be (partly) a mistake on my part and was canceled:

   https://list.orgmode.org/878r2b4dpy.fsf@localhost/T/#m48b7ea939117f241069fafbcf3726587837f3e70

But there is still a doc bug: since the default value of
`org-html-head-include-scripts' was changed to `nil' in Org 9.5, the
functionality described in the `Literal Examples' section of the manual
is no longer enabled by default. The attached patch adds a footnote to
describe how to enable that functionality. Thanks to user @JeanPierre on
Emacs SE for the original question and the push for the doc patch:

   https://emacs.stackexchange.com/questions/80783/org-mode-export-to-html-onmouseover-highlighting-of-referenced-code-lines