<..html latex env..>+
\ifx \flushleft\:UnDef \else
\append:def\flushleft{\linepenalty=10 }
\fi
-_-_-
<..html latex env..>+
\append:def\flushright{\linepenalty=10 \ifx \EndPicture\:UnDef
\parfillskip=\@flushglue
\leftskip=\z@skip \rightskip=\@flushglue
\fi}
-_-_-
The following have a problem of lack of space below and above them, because we don’t want space on the margins. Above we tried to force the extra space.
Users might not be consistent to whether spaces are introduced at start and end of lines.