I'm using Marco Daniel's fullwidth package, detailed in this answer. I want all of my text in fullwidth to be inseparable (and to begin and end with long black lines), so I am currently doing the following:
\documentclass[11pt,a4paper]{memoir}
\usepackage[outermargin=-4cm,]{fullwidth}
\begin{document}
\begin{minipage}{\linewidth}
\begin{fullwidth}[width=\linewidth+4cm]
\medskip
This is very long, but because it is in the fullwidth environment,
it extends into the full length of the page
before a line break occurs.
\medskip
\end{fullwidth}
\end{minipage}
\end{document}
This works, but it does give me the following warnings:
" fullwidth uses option nobreak Warning: \def on input line 15"
"Package fullwidth Warning: The environment is empty (fullwidth) on input line 15."
along with an
"Overfull \hbox"...
These warning do not occur when I remove the minipage command. What is causing these warning, and how can I get rid of them?
Also, can I define a macro so that whenever I just write \begin{fullwidth}, LaTeX will automatically do \begin{minipage}{\linewidth} \begin{fullwidth}[width=\linewidth+4cm] \medskip?
UPDATE:
@cmhughes provided a perfect solution to the "define a macro" question. However, his use of the nobreak option in fullwidth instead of using minipage doesn't work. Here's the gist of the problem with it:
If I use [leftmargin = -4cm] OR [outermargin = -4cm], then the fullwidth text extends into the correct margin (the outer margin) on odd pages, and the incorrect margin (the inner margin) on even pages. If I use [rightmargin = -4cm] OR [innermargin = -4cm], then the fullwidth text extends into the correct margin (the outer margin) on even pages, and the incorrect margin (the inner margin) on odd pages. Herein lies the problem: the nobreak option messes up relative positioning, so that outermargin and innermargin only behave like leftmargin and rightmargin.
Please read the comments on his answer for a more detailed discussion. As of now, I'm looking for something that can fix the warnings given by using minipage, or that can use the nobreak option correctly...