Footnote taking width of *both* body and margin note

Question

I am wondering how can I adjust geometry parameters (or using other packages) to make the layout of footnote taking the width of BOTH body and margin note.

Thanks,

Answer 1

It can be done, provided you use only onesided typesetting, or footnotes on left hand pages will appear as hanging from nowhere.

\documentclass[a4paper]{article}

\usepackage{lipsum}

\usepackage{etoolbox}
\makeatletter
\patchcmd\@footnotetext
  {\hsize\columnwidth}
  {\hsize\columnwidth\advance\hsize\marginparsep\advance\hsize\marginparwidth}
  {}{}
\makeatother

\begin{document}
a\footnote{\lipsum*[3]}\marginpar{Aaa bb cc dd ee ff gg hh ii jj kk ll mm nn}
\lipsum[1-10]
\end{document}

I find that the result shows just one thing: keep away!