Hi all,

I need a (pre-linebreak) callback to behave the same way with the
Context and Plain formats. *The sequence that nodes are traversed
in is very important.* Afaict the callback will have to be
registered as a “processors”/“before” nodes task. However, the
behavior is not identical:

1.  If the list contains a vlist or hlist, the callback is
    applied first on the inner list and then on the outer list.
    (Guess: it’s applied on the hpack_filter as well?)

2.  In Plain, glyph nodes have subtype 0 (GLYPH_CHARACTER), while
    in Context it’s 1 (GLYPH_LIGATURE).

Example code is appended.

Questions:
  - Which node task gets me a behavior similar to the raw
    pre_linebreak_filter?[*]
  - Does the difference wrt node subtype matter assuming I only
    (a) copy glyph nodes and (b) manipulate their .char field?

Any insights on this matter would be greatly appreciated. Regards
Philipp

[*] If this is not possible|recommended, what would a clean
    solution look like?