function checkEmpty() {
  if (document.VrijZoeken.searchvalue.value != '') {
    //openTarget(document.forms[0], 'zoeken','500','500','yes');
    return true;
  } else {
    return false
  }
}

function openTarget(form,name,w,h,scroll) {
    LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
    TopPosition = (screen.height) ? (screen.height-h)/2 : 0;
    settings ='height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars=yes,resizable=yes'
    form.target = name
    win = window.open('',name,settings);
    win.focus();
}

function Proces(verder) {
    var bfound = false;
    var result1="optThema=";
    var thisform = document.parameterZoeken;
    if (thisform.optThema.selectedIndex !=0) {
        result1+=thisform.optThema.options[thisform.optThema.selectedIndex].value;
    }
    result1=unescape(result1);

    var result2="&optActiviteit=";
    if (thisform.optActiviteit.selectedIndex !=0) {
        result2+=thisform.optActiviteit.options[thisform.optActiviteit.selectedIndex].value;
    }
    result2=unescape(result2);
    if (verder==1) {
      document.location = "search_result.asp?"+result1+result2;
    } else {
      //alert("dummy wordt: calculatesearch.asp?"+result1+result2);
      parent.dummy.location = "calculatesearch.asp?"+result1+result2;
    }
}