function expand(id,img)
{
  if(document.getElementById(id).style.display == 'block') {
    document.getElementById(id).style.display = 'none';
    document.getElementById(img).src = 'http://oefenbank.infectieziekten.eu//cms/cms_files/' + 'img/plus.gif';
  } else {
    document.getElementById(id).style.display = 'block';
    document.getElementById(img).src = 'http://oefenbank.infectieziekten.eu//cms/cms_files/' + 'img/min.gif';
  }
}
function openHelp(url, id) {
    var top = (screen.height / 2) - 250;
    var left = (screen.width / 2) - 350;
	  window.open( url + '?action=index&item=' + id, '_blank', 'left='+ left +', top='+ top +', width=700, height=500, scrollbars=no, toolbar=no, location=no' );
}