How to create a shade box that covers the whole footnotes area?

Question

I would like to shade the whole footnote area (bottom of the page). Does anyone know, if it can be done ?

Edit : Using the answer provided, the text direction commands \setRL and \setLR, from the Bidi package, get ignored. Here is an example :

%!TEX TS-program = xelatex
%!TEX encoding = UTF-8 Unicode
\documentclass[a4paper,12pt]{article}
\TeXXeTstate=1


\usepackage{framed}
\usepackage{xunicode}
\usepackage{xltxtra}
\usepackage{polyglossia}
\usepackage{bidi}
\usepackage{fontspec}
\usepackage{color}

\defaultfontfeatures{Scale=MatchLowercase}
\setmainfont{Times New Roman}
\newfontfamily{\sbl}[Script=Hebrew]{SBLHebrew}
\setmainlanguage{english}
\setotherlanguage[numerals=hebrew]{hebrew}


%colored footnotes

\def\colorftns#1{%
\nointerlineskip\hbox{\fboxsep0pt \colorbox{yellow}{\box#1}}}
\let\oldfootnoterule\footnoterule 
\def\footnoterule{\oldfootnoterule\let\unvbox\colorftns}

\begin{document}
\setRL
\H
h e b r e w t e x t   \setLR\footnote{a b c d e f} \setRL
\end{document} 

Answer 1

This removes some of the flexible space between footnotes in order to box and colour the area, but is probably OK in practice.

\documentclass{article}
\usepackage{color}


\def\colorftns#1{%
\nointerlineskip\hbox{\fboxsep0pt \colorbox{yellow}{\box#1}}}

\let\oldfootnoterule\footnoterule
\def\footnoterule{\oldfootnoterule\let\unvbox\colorftns}



\begin{document}

aaa\footnote{one two three}

aaa\footnote{four five six}

aaa\footnote{red blue green

}
\end{document}