lilypond-book fragment with ties/slurs continuing over the end of the fragment

[Vaclav Smilauer]

(I posted this message to the general mailing list and apparently there is no
such feature in lilypond to make that happen so I turn over here)

I would like to typeset one-line (one system) of music that has ties and/or
slurs continuing over the end, to the (hypothetical) second system. The system
is block-aligned (in LaTeX). I tried two lilypond-only solutions:

1. "... | c1 ~| \hideNotes\stopStaff c": the staff was aligned as if the hidden
bit was there (i.e. it was narrower than \hsize); also, the tie did not look as
pretty as it should.

2. "... | c1 ~| \break\hideNotes\stopStaff c": the alignment was perfect, the
tie was also perfect, but I got clef, bar number and the other part of the
broken tie printed.

Since there is the --preview feature of lilypond, I think that it would be
enough if lilypond-book passed that option to lilypond and then renamed the
*.preview.* file as if it were the whole output of lilypond, ending at \break.

Is such approach acceptable? Should I try (lilypond-book is "python", not
python; sigh) and send a patch? What should this option be called? "oneliner"?
"Preview" is clearly not appropriate. Or is it achievable from within .ly, after
all?

Regards, Vaclav Smilauer