old way of vertically centering refrain no longer works

[Ted Walther]

Carl Sorensen referred me a few months back to the hymn "Near the Cross"
from Mutopia as an example of how centering a refrain is supposed to
work.

I am now using lilypond 2.9.17.  Near the Cross was coded for 2.4.2

The method used does not work now, and after further experimentation, I
am not sure it ever worked.

The markup contained the following macros:

setLyricsExtent = \set Lyrics.minimumVerticalExtent = %#'(-1.0 . 1.2)
setLyricsExtentRef = \override Lyrics #'minimumVerticalExtent = %#'(-1.3 . 1.4)
setStaffExtentA = \set Staff.minimumVerticalExtent = #'(-6 .  1)
setStaffExtentB = \set Staff.minimumVerticalExtent = #'(-1 .  5)

setLyricsExtent was put at the beginning of each stanza.

setLyricsExtentRef was put at the beginning of the refrain, which was
included at the end of the \lyrics { } block for the first stanza.

Compiling it under 2.9.17 showed that the refrain was not centered.  It
appeared to be centered in the original version because the refrain had
an entire line to itself; it did not start on a line that contained all
four verses.

I did some digging, and replaced the definitions according to the
manual:

% \override Staff.VerticalAxisGroup #'minimum-Y-extent = #'(-3 . 3)
setLyricsExtent = \override Staff.VerticalAxisGroup #'minimum-Y-extent = 
#'(-1.0 . 1.2)
setLyricsExtentRef = \override Staff.VerticalAxisGroup #'minimum-Y-extent = 
#'(-1.3 . 1.4)

These changes did not work either, but they did get rid of the error
message "warning: not a grob name, `Lyrics'"

So, my question is, what is the correct way to vertically center a
refrain shared by several stanzas?

I have not read the entire manual, but I did read the sections on text
markup and lyrics and poked through it using the find function in my
browser for keywords and didn't find anything directly relevant.

Ted

--
          It's not true unless it makes you laugh,                           
     but you don't understand it until it makes you weep.

Eukleia: Ted Walther
Address: 2459 E 41 Ave, Vancouver, BC  V5R2W2 (Canada)
Contact: 604-435-5787