function get_windowHeight()
{
   var myWidth = 0, myHeight = 0;
   if( typeof( window.innerWidth ) == 'number' )
   { //Non-IE
      myHeight = window.innerHeight;
   }
   else
   {
      if ( document.documentElement && ( document.documentElement.clientWidth ||    document.documentElement.clientHeight ) )
   { //IE 6+ in 'standards compliant mode'
      myHeight = document.documentElement.clientHeight;
   }
   else
   {
      if ( document.body && ( document.body.clientWidth || document.body.clientHeight ) )
      { //IE 4 compatible
         myHeight = document.body.clientHeight;
      }
   }
}

   //alert(myHeight);
   document.getElementById('framehoogte').style.height = (myHeight - 255) + 'px';
   //document.getElementById('frames').style.height = myHeight - 235;
   //var x=document.getElementById('tabel').rows
   //x[0].height=myHeight - 250;
   //return myHeight;
   //alert('eerst');
   //alert(document.getElementById('framehoogte').style.height);
}