function rollout(fieldname, id) {
  var display_id= fieldname+'_'+id;
	
    // controlleren of hij gedisplayed wordt
	if(document.getElementById(display_id).style.display=='none') {
		var show='0';
	}else if(document.getElementById(display_id).style.display=='block') {
		var show='1';
	}

	if(show=='0') {
		document.getElementById(display_id).style.display='block';
	} else {
		document.getElementById(display_id).style.display='none';
	}
}