Columns odd vertical alignment in multicol

Question

This code

\documentclass[12pt]{article}
\usepackage[parfill]{parskip}
\usepackage{multicol}

\widowpenalties 2 9999 9999

\begin{document}
\setlength\baselineskip{4ex plus 2ex minus 2ex}

\begin{multicols}{2}
    A\hrulefill1\newline
    A\hrulefill2\newline
    A\hrulefill3\newline
    A\hrulefill4\newline\par
    B\hrulefill1\newline
    B\hrulefill2\newline
    B\hrulefill3\newline
    B\hrulefill4\newline
    B\hrulefill5\newline\par
\end{multicols}

\end{document}

generates this

The automatic choice for the base line skip values looks odd, because the two columns have almost the same vertical size, but not quite.

Is there a way to achieve vertical justification, so that the last line of the first column in the same vertical position as the last line of the second column?

Answer 1

\newline\par you should never have \\ or \newline at the end of a paragraph. You are forcing a line whch has no text (and underfull box warnings) the two columns do have the same vertical size:

Do not ignore the warnings

Underfull \hbox (badness 10000) in paragraph at lines 11--14


Underfull \hbox (badness 10000) in paragraph at lines 15--19

which was warning about all white lines in each paragraph, and also forcing you to use \widowpenalties 2 as the visible last line was not the last.

It is easier to see what is happening if you have text on the last line of the paragraph, which also removes the warning

\documentclass[12pt]{article}
\usepackage[parfill]{parskip}
\usepackage{multicol}

\widowpenalties 2 9999 9999

\begin{document}
\setlength\baselineskip{4ex plus 2ex minus 2ex}

\begin{multicols}{2}
    A\hrulefill1\newline
    A\hrulefill2\newline
    A\hrulefill3\newline
    A\hrulefill4\newline  xxx\par
    B\hrulefill1\newline
    B\hrulefill2\newline
    B\hrulefill3\newline
    B\hrulefill4\newline
    B\hrulefill5\newline xxx\par
\end{multicols}

\end{document}