\environment back-0

\startuseMPgraphic{mpos:par:color}
  for i=1 upto nofmultipars :
    fill multipars[i] withcolor
      if     multikind[i]="single" : "darkgray" ;
      elseif multikind[i]="first"  : "red" ;
      elseif multikind[i]="middle" : "green" ;
      elseif multikind[i]="last"   : "blue" ;
      else                         : "black" ;
      fi ;
  endfor ;
\stopuseMPgraphic

\definecolumnset
  [three]
  [n=3,
   distance=5mm]

\definetextbackground
  [shade]
  [location=paragraph,
   mp=mpos:par:color,
   before=\blank,
   after=\blank]

\starttext

\startcolumnset[three]

  \dorecurse {20} {
    \starttextbackground[shade]
      \simulatewords[n=50,m=500,min=1,max=5,color=gray]%
    \stoptextbackground
  }

\stopcolumnset

\stoptext