Re: misalignment in header -- fill-line issue?

On 2025-06-06 00:02, Werner LEMBERG wrote:
>>>     But I still think that there's a problem with \fill-line. I
>>>     don't think it should cause the word "Composer" to protrude
>>>     past the end of the staff when there is plenty of room for it
>>>     to fit properly right-aligned to the end of the staff.
>>> 
>>> Yes, this is definitely a flaw in the current implementation of
>>> \fill-line.
> 
> I don't think so.  IMHO it's rather that the documentation of
> `\fill-line` is not adequate to what this function really does, namely
> to split a line into N equally large regions for N arguments, with the
> text in the leftmost region left-aligned, the text in the rightmost
> region right-aligned, and the remaining text strings centered in the
> respective regions.  In many cases it is plain ugly if the middle part
> is moved to the right because the left part is little bit longer.
> Consider this example.
[snip]
>> This being the case, should a bug be added to the bug tracker?  And
>> if so, should I do it?  Or would it be better if someone else did?
[snip]
> However, for these two
> 
> * Improve documentation of `\fill-line`.
> 
> * The default `\bookTitleMarkup` should be made more sophisticated,
>   recognizing that `\fill-line` should be called with only two
>   arguments if the middle element (i.e., `header:instrument`) is
>   empty.
> 
> we don't have issues, so yes, please add two new ones, also adding
> code and images to show what's going on.

I have submitted a new issue for improving the documentation of 
\fill-line:
https://gitlab.com/lilypond/lilypond/-/issues/6824

I did not submit an issue for improving \bookTitleMarkup. My current 
thought is that it shouldn't be necessary to do so once the bug in 
\fill-line is fixed:
https://gitlab.com/lilypond/lilypond/-/issues/6823

James