I slightly modified the code and the output is now better than before, please add it to the wiki.

\startuseMPgraphic{tableborders}

draw leftboundary OverlayBox withpen pensquare scaled \frameddimension {leftrulethickness} ; draw rightboundary OverlayBox withpen pensquare scaled \frameddimension {rightrulethickness} ; draw topboundary OverlayBox withpen pensquare scaled \frameddimension {toprulethickness} ; draw bottomboundary OverlayBox withpen pensquare scaled \frameddimension{bottomrulethickness} ;

clip currentpicture to OverlayBox leftenlarged (\frameddimension {leftrulethickness}/2) rightenlarged (\frameddimension {rightrulethickness}/2) topenlarged (\frameddimension {toprulethickness}/2) bottomenlarged (\frameddimension{bottomrulethickness}/2) ;

setbounds currentpicture to OverlayBox ;

\stopuseMPgraphic

\defineoverlay[tableborders][\useMPgraphic{tableborders}]

\startsetups tableborders

\setupTABLE [ background={color,tableborders}, frame=off, backgroundoffset=0pt, leftrulethickness=\framedparameter{rulethickness}, rightrulethickness=\framedparameter{rulethickness}, toprulethickness=\framedparameter{rulethickness}, bottomrulethickness=\framedparameter{rulethickness}]

\setupTABLE[row] [odd] [backgroundcolor=lightgray] \setupTABLE[row] [first][backgroundcolor=gray,bottomrulethickness=2pt] \setupTABLE[row] [last] [toprulethickness=2pt,bottomrulethickness=2pt] \setupTABLE[first][last] [leftrulethickness=2pt] \setupTABLE[last] [last] [rightrulethickness=2pt]

\stopsetups

\starttext

\bTABLE \dorecurse{7}{\bTR\dorecurse{3}{\bTD#1-##1\eTD}\eTR} \eTABLE

\blank

\bTABLE[setups=tableborders] \dorecurse{7}{\bTR\dorecurse{3}{\bTD#1-##1\eTD}\eTR} \eTABLE

\stoptext

Wolfgang

Thanks so much for this, it looks really nice (booth the implementation and the output). I've added this to the TABLE wiki since this example above is a table, however I suspect this would work for any "frame". Is there a reason why this doesn't work with mkii? I'm not using mkii for a long time now, just the wiki didn't rendered this example properly and also on my local machine it didn't show the thick rules, works perfectly with mkiv though. Cheers Adam