ledpar ignores \startstanzahook (not able to put extra space between stanzas)

Question

The ledmac/-par manual says that I may use \startstanzahook to get extra space between stanzas. But it works only in normal verses an not in parallel typsetting. The following example may give a better idea what I mean:

% XETEX-DOCUMENT
\documentclass{scrartcl}
\usepackage{xltxtra}
\usepackage{ledmac,ledpar}
    \maxchunks{100}
    \newcommand*{\startstanzahook}{\vspace{\baselineskip}}
\begin{document}
% works (vspace between stanzas):
\beginnumbering
\setstanzaindents{2,0,0}
\stanza 
    Non ego Caesareas, non arma virumque, & 
    sed chitaram plectrumque cano nec inutile numen 
\& 
\stanza 
    Doctus in Arcadiis vivebat musicus oris, & 
    clarus circa urbes et famae voce lyraeque.
\&
\endnumbering

% doesn't work (no vspace):
\begin{pages}
\begin{Leftside}
    \beginnumbering
    \setstanzaindents{2,0,0}
    \stanza 
        Non ego Caesareas, non arma virumque, & 
        et lyricam poterit, nisi centum vocibus, artem? 
    \& 
    \stanza 
        Doctus in Arcadiis vivebat musicus oris, & 
        vicina quondam late celebratus in urbe 
    \& 
    \endnumbering
\end{Leftside}
\begin{Rightside}
    \beginnumbering
    \setstanzaindents{2,0,0}
    \stanza 
        Non ego Caesareas, non arma virumque, & 
        et lyricam poterit, nisi centum vocibus, artem? 
    \& 
    \stanza 
        Doctus in Arcadiis vivebat musicus oris, & 
        vicina quondam late celebratus in urbe 
    \& 
    \endnumbering
\end{Rightside} 
\Pages 
\end{pages} 
\end{document}

Is there any way to instert extra space between stanzas in parallel-mode?

Answer 1

The trick is to include the material to be inserted between the stanzas into a seperate \pstart ... \pend construct, otherwise it won't be processed by the delayed output routine of ledpar. So you'll have to replace

\newcommand*{\startstanzahook}{\vspace{\baselineskip}}

by

\def\endstanzaextra{\pstart\skipnumbering\strut\pend}

in order to add one extra line between the stanzas (with the \strut macro). Note that this hook triggers at the end of each stanza, not at the beginning. This is because the extra line is included in the line numbering by default - in order to avoid this, \skipnumbering is called, which is only possible at the end of the stanza.