function toonKnop(knopId){
  document.getElementById(knopId).src = "/Dordrecht/gx/ZwfcawzHsB.gif";
  document.getElementById(knopId).width = 16;
  document.getElementById(knopId).height = 16;
}

function highlight(topmenu){
  getElementById(topmenu).style.background='red';
}