>> Yeah, it seems that this is the case. Can you try an unpure-pure
>> container to get a better vertical space estimate for `Y-extent`?
>> See
>>
>>
>> https://lilypond.org/doc/v2.25/Documentation/extending/unpure_002dpure-containers
>
> Is the idea to solve the problem with an unpure-pure container? Or
> is this an experiment, which, if it works, will lead to declaring
> sectionLabel as a pure function?
I don't know, sorry. My experience with unpure-pure containers is
zero; my advice is just an educated guess based on similar stuff that
we've seen on the mailing lists, namely to make LilyPond provide a
larger space default than it currently does.
Werner
