Dutch 'trema' not handled as required in hyphenation

[Jürgen Spitzmüller]

Am Sonntag, dem 28.05.2023 um 11:16 +0200 schrieb R. H. van der Gaag:
> Hi there fellow LyXers,
> I noticed that the Dutch ‘trema’ (the dots above ü ä ï ö ë) isn’t
> removed when the word is hyphenated directly before the letter with
> the trema (it should, to comply with grammar rules. In LaTeX, 
> 
> > \usepackage{newunicodechar}
> > \makeatletter
> > \newunicodechar{ë}{\@trema e}
> > \newunicodechar{ï}{\@trema i}
> > \newunicodechar{ö}{\@trema o}
> > \newunicodechar{ä}{\@trema a}
> > \newunicodechar{ü}{\@trema u}
> > \makeatother
> > 
> 
> takes care of this, but adding the same lines to the preamble in LyX
> doesn’t. Am I overlooking something? How can I make this work?

Is this with babel or polyglossia?

With babel, there is the shorthand "a (etc.) to implement this.
Polyglossia doesn't support this yet (worth a feature request
at https://github.com/reutenauer/polyglossia/issues)

-- 
Jürgen