I have an environment with a minipageof the length \linewidth-\parindent (using the calc package). When I stick this in a place where \leftskip=\parindent it protrudes in the margin. Shouldn't \linewidth adapt to these new dimensions and keep the minipage inside the margin?
\documentclass{article}
\usepackage{blindtext}
\usepackage{calc}
\newenvironment{env}
{\hfill\begin{minipage}{\linewidth-\parindent}\bf}
{\end{minipage}}
\begin{document}
\tiny
\blindtext
\begin{env}
\blindtext
\end{env}
\blindtext
\setlength{\leftskip}{\parindent}
\blindtext
\begin{env}
\blindtext
\end{env}
\end{document}

EDIT: With the hints from David I found what I needed from this question (is this a duplicate?):
\newenvironment{env}
{\list{}{}\item\relax
\nointerlineskip\leavevmode}
{\endlist}
This indents the margin via list (like LaTeXs quote) and \nointerlineskip\leavevmode fixes problems with missing items.

changepagepackage? It will surely do what you want to achieve. Tell me if you want me to post a MWE or if you want to give it a try first then that's fine as well. By the way, try using\bfseriesinstead of\bf. Just a suggestion. – azetina Jun 06 '14 at 17:24changepageandadjustwidthI get 'maybe a missing \item' error messages with line references to what seems to be all\labelcommands. – Andreas Jun 06 '14 at 20:03