var xmlHttp_element
function get_subjects(grade, subject, width_)
{
	xmlHttp_element=GetXmlHttpObject()
	if (xmlHttp_element==null)
	{
		alert ("Browser does not support HTTP Request")
		return
	} 
	var url="get_subjects.weml"
	url=url+"?grade="+grade
	url=url+"&subject="+subject
	url=url+"&width_="+width_
	url=url+"&sid="+Math.random()
	xmlHttp_element.onreadystatechange = function () { set_subjects(); };
	xmlHttp_element.open("GET",url,true)
	xmlHttp_element.send(null)
}

function set_subjects()
{
	if (xmlHttp_element.readyState==4 || xmlHttp_element.readyState=="complete")
	{
		document.getElementById("subjects_dropdown").innerHTML=xmlHttp_element.responseText 
	}
}


function GetXmlHttpObject()
{ 
	var objXMLHttp=null
	if (window.XMLHttpRequest)
	{
		objXMLHttp=new XMLHttpRequest()
	}
	else if (window.ActiveXObject)
	{
		objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
	}
	return objXMLHttp
}