var ajaxreq=false, ajaxCallback;
function ajaxRequest(filename)
{
	try
	{
		// Firefox / IE7 / ...
		ajaxreq= new XMLHttpRequest();
	}
	catch(error)
	{
		try
		{
			// IE 5 / IE 6
			ajaxreq = new ActiveXObject("Microsoft.XMLHTTP");
		}
		catch(error)
		{
			return false;
		}
	}
	ajaxreq.open("GET",filename);
	ajaxreq.onreadystatechange = ajaxResponse;
	ajaxreq.send(null);
}

function ajaxResponse()
{
	if(ajaxreq.readyState != 4) return;
	if(ajaxreq.status == 200)
	{
		// sikeres kérelem
		if(ajaxCallback) ajaxCallback();
	}
	else alert("Hiba: " + ajaxreq.statusText);
	return true;
}