function ver_ventana(){
	var ventana = document.getElementById('ventana');
	
	var xmlhttp = Ajax();
	
	var url = "ventana.php";
	xmlhttp.open("POST", url, true);
	xmlhttp.onreadystatechange = function() {
		if (xmlhttp.readyState == 4) {
			ventana.innerHTML = xmlhttp.responseText;
			ventana.style.display = "block";
		}
	};
	xmlhttp.send(null);
	
	}
	
function cerrar(){
	var ventana = document.getElementById('ventana');

			ventana.style.display = "none";

	}