var agendaVenster;
function closeChildren() {
  if(agendaVenster && !agendaVenster.closed) {
    agendaVenster.close();
  }
}

function open_event(date_stamp) {
  document.getElementById('subpage') ? url = "../" : url = "";
  url+= "inc/calendar2.php?show_event=true&event_date=" + date_stamp;
  var agendaVenster = window.open(url,'','scrollbars=no,menubar=no,height=400,width=300,resizable=no,toolbar=no,location=no,status=no');
}