Using \prevgraf in \multirow cells

Question

Questions like alignment-in-longtable are quite common. One of the possible solutions is use of the multirow cells, where with the option t or b the contents of the cells are aligned to the top or bottom of the cell. The problem here is to set the number of lines of text in the adjacent cells. It can be determined by manual counting of rows, however its automatic count is preferable.

An elegant solution was shown @David Carlisle in edit to my answer on the aforementioned question, where he show use of the endgraf macro. This solution work fine, however, I notice a bit annoying problem: it also insert empty row in the cell:

\documentclass{scrbook}
\usepackage{multirow, xltabular}
\newcolumntype{L}{>{\raggedright\arraybackslash}X}
\usepackage{lipsum}
\begin{document}
    \begin{xltabular}{\linewidth}{@{} l|L<{\endgraf\xdef\zzz{\the\prevgraf}}@{}c @{}}
Column 1 & Column 2     & Column 3                      \  \hline
top      &  \lipsum[1]  & \multirow[b]{\zzz}{}{bottom} \  \hline
top      & \lipsum[11]  & \multirow[b]{\zzz}{}{bottom} \  \hline
    \end{xltabular}
\end{document}

Is there a way to remove this vertical space?

Answer 1

At the end of an X cell (which is p in disguise) LaTeX inserts a \strut. In your case this happens after a paragraph has been formed.

You can remove the blank line so created by adding a negative vertical space.

\documentclass{scrbook}
\usepackage{multirow, xltabular}
\usepackage{lipsum}
\newcolumntype{L}{>{\raggedright\arraybackslash}X}
\newcommand{\countlines}[1]{%
  \vspace{-\normalbaselineskip}\strut
  \endgraf
  \xdef#1{\the\prevgraf}%
}
\begin{document}
\begin{xltabular}{\linewidth}{@{} l|L<{\countlines{\zzz}}@{}c @{}}
Column 1 & Column 2    & Column 3                      \  \hline
top      & \lipsum[1]  & \multirow[b]{\zzz}{}{bottom} \  \hline
top      & \lipsum[11] & \multirow[b]{\zzz}{}{bottom} \  \hline
\end{xltabular}
\end{document}