// JavaScript Document
var xmlHttp
function carrega_combo(id)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var parametros = "id_tipo=" + encodeURI( document.getElementById('tipos').value );
var page="carrega_combo.php";
xmlHttp.onreadystatechange=mostra_status
xmlHttp.open("POST",page,true)
xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlHttp.setRequestHeader("Content-length", parametros.length);
xmlHttp.setRequestHeader('Content-Type', "application/x-www-form-urlencoded; charset=iso-8859-1");
xmlHttp.send(parametros)
}


function mostra_status() 

{ 
if(xmlHttp.readyState == 1) { // Quando estiver carregando, exibe uma camada: Carregando...
document.getElementById('msg_load').style.visibility="visible";
}
if(xmlHttp.readyState == 4||xmlHttp.readyState=="Complete")
{ 
document.getElementById('msg_load').style.visibility="hidden";
document.getElementById('ajax_result').innerHTML=xmlHttp.responseText;

}

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