var _is_Opera = navigator.userAgent.indexOf("Opera") > -1; 
var _is_IE = navigator.userAgent.indexOf("MSIE") > 1 && !_is_Opera; 
var _is_Moz = navigator.userAgent.indexOf("Mozilla/5.") == 0 && !_is_Opera; 

/* Create a new XMLHttpRequest object to talk to the Web server */
var xmlHttp = false;
/*@cc_on @*/
/*@if (@_jscript_version >= 5)
try {
  xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
  try {
    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
  } catch (e2) {
    xmlHttp = false;
  }
}
@end @*/

if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
  xmlHttp = new XMLHttpRequest();
}

function ajax_get_subthemas(the_id) 
{
	//als thema niet leeg is, servercall wel uitvoeren
	//alert(escape(the_id));
	var url = "/InformCMS/ajaxservices/ajax_cv_cursus_d.php?the_id="+the_id ; 
	xmlHttp.open("GET", url, true);
	xmlHttp.onreadystatechange = updateSubthemas;
	xmlHttp.send(null);
}

function updateSubthemas() 
{
  if (xmlHttp.readyState == 4) 
  {
    //var response = xmlHttp.responseText;
    var xmlDocument = xmlHttp.responseXML;
    vulSelectBoxSubthemas(xmlDocument);
  }
}

function vulSelectBoxSubthemas( xmlDocument ) 
{
	//xmlfile laden die doorgegeven wordt vanuit ajax service
	var zipfile=xmlDocument.getElementsByTagName('zipfile');

	//selectbox subthema's laden en leegmaken
	var sel_sub_id = document.getElementById('sel_sub_id');
	sel_sub_id.options.length = 0;	
	
	if ( _is_IE && zipfile[0].childNodes.length == 0 )
	{
		sel_sub_id.options[0] = new Option("Geen subthema's binnen dit thema'",0);
		return;
	}
	
	if ( _is_Moz && zipfile[0].childNodes.length == 1 )
	{
		sel_sub_id.options[0] = new Option("Geen subthema's binnen dit thema",0);
		return;
	}
	
	//als er wel subthema's gevonden werden, selectbox opvullen
	for (i=0; i < zipfile[0].childNodes.length ; i++)
	{
		var sub_id = xmlDocument.getElementsByTagName('sub_id').item(i).firstChild.data;
		var sub_omschr = xmlDocument.getElementsByTagName('sub_omschr').item(i).firstChild.data;
		sel_sub_id.options[i] = new Option(sub_omschr, sub_id);
		//eerstgevonden subthema selecteren
		if ( i == 0)
		{
			sel_sub_id.value = sub_id;
		}
	}
	
	sel_sub_id.style.width = '230px';
}