Chord-name-engraver plus capo

[Wols Lists]

 address@hidden ~/gitstuff/music/Hymnal/Choruses $
~/gitstuff/lilypond/out/bin/lilypond HeGaveMeBeautyForAshes.ly | tee chords
GNU LilyPond 2.13.30
Processing `HeGaveMeBeautyForAshes.ly'
Parsing...
Interpreting music...
warning: cannot find property type-check for `capoFret'
(translation-type?).  perhaps a typing error?
warning: doing assignment anyway
/home/anthony/gitstuff/lilypond/out/share/lilypond/current/scm/chord-ignatzek-names.scm:216:16:
In procedure car in expression (car in-pitches):
/home/anthony/gitstuff/lilypond/out/share/lilypond/current/scm/chord-ignatzek-names.scm:216:16:
Wrong type (expecting pair): ()


Learning a bit at a time ... how do I add properties? I've used "\set
ChordNames.capoFret = #3", but it's a new property, and it's objecting,
as you can see. I've added it to the "read" section of the
ADD_TRANSLATOR macro of chord-name-engraver.cc, but I'm guessing that
tells the engraver to use it, it doesn't tell lily that the property
exists ...

(the other stuff I know what's triggering it, I'll investigate the cause
later ...)

Cheers,
Wol