\startuseMPgraphic{mp_frame_left}
  draw leftboundary OverlayBox 
    withpen pensquare scaled \frameddimension{leftrulethickness}
    withcolor \MPcolor{\framedparameter{leftframecolor}} ;
  setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\startuseMPgraphic{mp_frame_right}
  draw rightboundary OverlayBox 
    withpen pensquare scaled \frameddimension{rightrulethickness}
    withcolor \MPcolor{\framedparameter{rightframecolor}} ;
  setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\startuseMPgraphic{mp_frame_top}
  draw topboundary OverlayBox 
    withpen pensquare scaled \frameddimension{toprulethickness}
    withcolor \MPcolor{\framedparameter{topframecolor}} ;
  setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\startuseMPgraphic{mp_frame_bottom}
  draw bottomboundary OverlayBox 
    withpen pensquare scaled \frameddimension{bottomrulethickness}
    withcolor \MPcolor{\framedparameter{bottomframecolor}} ;
  setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\installleftframerenderer   {mp} {\useMPgraphic{mp_frame_left}}
\installrightframerenderer  {mp} {\useMPgraphic{mp_frame_right}}
\installtopframerenderer    {mp} {\useMPgraphic{mp_frame_top}}
\installbottomframerenderer {mp} {\useMPgraphic{mp_frame_bottom}}

\setupframed
  [     leftframecolor=\framedparameter{framecolor},
       rightframecolor=\framedparameter{framecolor},
         topframecolor=\framedparameter{framecolor},
      bottomframecolor=\framedparameter{framecolor},
     leftrulethickness=\framedparameter{rulethickness},
    rightrulethickness=\framedparameter{rulethickness},
      toprulethickness=\framedparameter{rulethickness},
   bottomrulethickness=\framedparameter{rulethickness}]

\endinput