\setuppapersize
  [A4][A3]

\setuplayout
  [location=middle]

\setupalign[tolerant,stretch]

\startuseMPgraphic{contrast}
    fill OverlayBox withcolor red ;
\stopuseMPgraphic

\defineoverlay
  [contrast]
  [\useMPgraphic{contrast}]

\showframe

\setuppagenumbering
  [alternative=doublesided]

\definecolumnset
  [mycolumnset]
  [n=2]

\definecolumnsetarea
  [whatever]
  [left]
  [x=1,y=1,nx=3,ny=20,
   background=contrast,
   state=start,
   leftoffset=1cm,
   rightoffset=1cm]

\setupcolumntextareatext
  [whatever]
  [HI THERE]

\definecolumntextarea
  [title]
  [x=1,y=4,nx=2,ny=7,state=start]

\setupcolumntextareatext
  [title]
  [\ruledvtop to 5cm{\hsize 4cm a\\b\\b\\d}]

\starttext

\startcolumnset[mycolumnset]

    \dorecurse{15}{\input tufte\par}

\stopcolumnset

\stoptext

