\begin{framed}
  ...
  \end{framed}

  \begin{shaded}
  ...
  \end{shaded}

  \begin{snugshade}
  ...
  \end{snugshade}

  \newenvironment{shadedf}{%
    \def\FrameCommand{\fcolorbox{black}{shadecolor}}%
    \MakeFramed {\advance\hsize-\width \FrameRestore}%
    }%
  {\endMakeFramed}

  \begin{document}

  \definecolor{shadecolor}{gray}{0.80}
  \begin{shadedf}
  ...
  \end{shadedf}

  \newenvironment{mybg}{%
     \def\FrameCommand##1{\fboxsep4pt
       \colorbox{cyan}{##1}}%
     \MakeFramed {\FrameRestore}}%
    {\endMakeFramed} 

  \begin{document}

  \begin{mybg}
  ...
  \end{mybg}

  \begin{leftbar}
  ...
  \end{leftbar}