Pseudo [Re]-surrecting: is there a \RemoveEmptyLyrics

[Alexander Kobel]

Dear all,

I want to typeset a little hymn with two stanzas and a common chorus. 
Easy-peasy if the chorus begins after a line break, tedious tweaking 
otherwise. I am aware of

http://www.lilypond.org/doc/v2.17/Documentation/snippets/vocal-music#vocal-music-vertically-centered-common-lyrics
which uses manual Y-offsets for the chorus lyrics in their first line. 
This time, I'm in a situation where the LyricExtender of the first 
chorus line extends over the line break, and I need to give separate 
extra-Y-offset = #0 for the broken extender. Bah. Yes, I can and will 
figure out how to do it if necessary, but...

... isn't there a clean way to make a lyrics context (centered between 
two others) not to take any space where there are no lyrics? Like going 
hara-kiri and resurrecting when the lyrics start? Or making the 
surrounding lyrics commit suicide? Or fake an empty Y-extent in the 
common lyrics context until the lyrics actually start?

I tried some approaches (see attached file): "Stealing" the Y-extent 
seems to work, but as soon as I go "backtodefaults" (line 6), the 
original Y-extent-calculation seems to carry over to the entire line, 
IIUC. Trying to kill the Y-extent of the stanza lyrics after they end 
changes nothing, unfortunately.

Any ideas? I'm not sure at all if this is connected to the original 
question of the thread (removing an empty context), since AFAICS it only 
applies to entire lines of the context. A related discussion is, e.g., here
  http://lists.gnu.org/archive/html/lilypond-user/2013-08/msg00530.html
with a link to
  http://www.hymnary.org/page/fetch/WASH1957/264/low
which shows what I want to achieve; several other threads are around, 
but all of them end up with the recommendation of using the manual 
offset tweaking from the snippet.


TIA,
Alexander

lyrics.png
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lyrics.ly
Description: Text Data