function ajaxPreencheCombo(action,value,idCombo) {

	var http_request = null;

	if (window.XMLHttpRequest) { // Mozilla, Safari, ...
    	http_request = new XMLHttpRequest();
	} else if (window.ActiveXObject) { // IE
	    http_request = new ActiveXObject("Microsoft.XMLHTTP");
	}

	//limpando select
	var element = document.getElementById("id_subgenero"); 
	var nItens = element.length;
	var i;
	for( i=nItens-1; i >=0; i-- ){
		element.options[i] = null;
	}
	element.options[0] = new Option('Carregando...','-1'); 

	http_request.onreadystatechange = function(){
		if (http_request.readyState == 4) {
			if (http_request.status == 200) {
				eval(http_request.responseText);
			} else {
			    alert("Problema ao carregar os subgeneros");
			}
		}
	};

	http_request.open('GET', '/servlet/'+action+'?value='+value+'&idCombo='+idCombo, true);
	http_request.setRequestHeader('Content-Type',"application/x-www-form-urlencoded; charset=iso-8859-1");
    http_request.setRequestHeader("Cache-Control", "no-store, no-cache, must-revalidate");
    http_request.setRequestHeader("Cache-Control", "post-check=0, pre-check=0");
    http_request.setRequestHeader("Pragma", "no-cache");
	http_request.send(null);

}