Hooks to set attributes for different parts of the page.

[Udi-Fogiel]

Brief outline of the enhancement

I'm not sure if it is already possible but it would be nice to have some hooks
to control the attributes (in the LuaTeX meaning) of different parts of a page,
i.e. page number, headings, footnotes, marginpars etc.

This is a similar concept to \normal color, but \normalcolor is used inside
the page body, having a separate hook for other parts would be nice. Maybe
one hook for all parts which are not the page body will suffice, but of course
will be less configurable.

One use case is a problem I'm facing in Udi-Fogiel/lua-lineno#1
but I don't think this is specific to this case. It's probably common to want different parts
of the page to behave differently, e.g. default colors for footnotes. OpTeX for example
provides \_resetattrs, see pages 114 and 120 of optex-doc.pdf.

I did not add minimal examples as i did not have a good idea for one. You can
explore the examples in the linked issue (the package is not released yet so I thought
adding it in a minimal example will add confusion).

[Udi-Fogiel]

It looks like I'm not the first one who thought it would be useful
https://github.com/zauguin/luaul/blob/4c90c40761a2f7f5f78f2e098e505db68afc0b67/lua-ul.dtx#L1251-L1255

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity.

[josephwright]

This will be part of the tagging project when we come to the output routine: it will be addressed when it is needed as part of the overall approach.

[FrankMittelbach]

tentatively added to Fall 2025 release