How do I create combinations without any vertical space?

The following test file

\definecombination
     [overviewpage]
     [distance=\zeropoint,
      inbetween=,
     ]

\starttext
\startcombination[overviewpage][2*2]
   {\framed{Hello}}{}%
   {\framed{Hello}}{}%
   {\framed{Hello}}{}%
   {\framed{Hello}}{}%
\stopcombination
\stoptext

gives the attached result. Note that there is still vertical space between 
the two rows. How can I get rid of this space?

Aditya