Microtype and quote environment leads to different indent of first line

Question

When the microtype package is loaded a quote environment which starts with punctuation marks is inconsistent "indented". The first line in the following minimal example is unaffected, i.e. at the same place as without the package, but the next two lines are pushed to the left. I realize that it is a feature of the microtype package to push punctuation marks into the margin, but here it looks quite ugly because it isn't consistent. The first line is most likely different because of the included \item in \begin{quote}.

Is there a way to get the indention consistent? Can I temporarly disable this feature of microtype just for this environment? I'm having such code in some package manuals where some verbatim code lines which start with "punctuation" like { inside a quote environment.

\documentclass{article}
\usepackage{microtype}
\begin{document}
text text text text text text text text text text text text text text text text
\begin{quote}
    ()\\
    ()\\
    ()
\end{quote}
text text text text text text text text text text text text text text text text
\end{document}

Answer 1

Main microtype features can be enabled or disabled on the fly using the \microtypesetup command. In this case we need to locally disable character protrusion:

\documentclass{article}
\usepackage{microtype}

\newenvironment{example}{\microtypesetup{protrusion=false}%
  \begin{quote}}{\end{quote}}

\begin{document}
text text text text text text text text text text text text text text text text
\begin{example}
    ()\\
    ()\\
    ()
\end{example}
text text text text text text text text text text text text text text text text
\end{document}

This will, of course, have effect on all characters, be it () or any other symbol. An interesting task would be to selectively disable this feature if it should be kept enabled for symbols other than ().

Answer 2

The suggested solution from the author of microtype is this:

\documentclass{article}
\usepackage{microtype}
\makeatletter
\newcommand*\protrudeleft[1]{%
    {\everypar{}%
     \setbox\z@\vbox{\noindent#1}%
     \vbadness=\@M
     \splittopskip=\z@
     \global\setbox\z@=\vsplit\z@ to \baselineskip
     \unvbox\z@ \global\setbox\z@=\lastbox
    }%
    \ifhbox\z@
      \leavevmode
      \kern\leftmarginkern\z@
    \fi
    #1}
\makeatother
\begin{document}
text text text text text text text text text text text text text text text
text
\begin{quote}
    \protrudeleft()\\
    ()\\
    ()
\end{quote}
text text text text text text text text text text text text text text text
text
\end{document}

Attention: You will perhaps have to put the argument of \protrudeleft in braces if is not a like here a simple character.

Answer 3

I'd define my own microtype-safe environment to consistently have protrusion everywhere. Adjust the 3em to your needs:

\documentclass{article}
\usepackage{microtype}
\newenvironment{mtsafequote}
    {\par\bgroup\leftskip=3em\rightskip=3em\noindent\ignorespaces}
    {\par\egroup\noindent}
\begin{document}
text text text text text text text text text text text text text text text text
\begin{mtsafequote}
    ()\\
    ()\\
    ()
\end{mtsafequote}
text text text text text text text text text text text text text text text text
\end{document}

Answer 4

Martin, here is the kernel of what is needed. I think you are better qualified than I am to wrap this up into a nicely robust redefined quote environment (or maybe fix it at the list, \item level):

\begin{quote}
    \quitvmode\kern\dimexpr-0.001em*\the\lpcode\font`(\relax()\\
    ()\\
    ()
\end{quote}