Turning off marginpar (marginparwidth) while in multicols environment

I'm trying to turn off marginpar when starting a new multicols environment with this:

\renewenvironment{multicols}[1]{%
  \let\oldmarginparwidth\marginparwidth 
  \setlength{\marginparwidth}{0}%
  \begin{multicols}{#1}
}{%
  \end{multicols}%
  \setlength{\marginparwidth}{\oldmarginparwidth}%
}

However, it doesn't work. What am I missing?

From stackoverflow

• I'm not sure exactly what you're looking for here, but generally marginpars aren't allowed in multicols already. From the multicol documentation:

  ...floats and marginpars are not allowed in the current implementation [This is dictated by lack of time. To implement floats one has to reimplement the whole LATEX output routine.].

• I have managed to get it working by using the chngpage package and defining a new environment which sets/resets different values before/after that environment.

  However, I still have a problem on the last page of each \chapter: header width on the last page of the chapter

• The command you've got there won't work mid-page, you need to use the changepage package to do that.

  \usepackage{changepage}
  

  I take it you're trying to take up the full width of the page. I nicked this from the tufte-latex class:

  First, define an 'overhang' amount that'll be added to the textwidth at the beginning and subtracted at the end:

  \newlength{\overhang}
  \setlength{\overhang}{\marginparwidth}
  \addtolength{\overhang}{\marginparsep}
  

  Then use \adjustwidth with the overhang amount when you want to remove marginpar space:

  \begin{adjustwidth}{}{-\overhang}
  % This will be displayed full-width
  \end{adjustwidth}{}{-\overhang}
  

  As Damien pointed out, you can still use marginpars like this, they'll just exceed the pagewidth. \multicols will prevent you from using floats, however.

  Hope that's what you need!