function Ajax() {
  try {
    request = new XMLHttpRequest();
  } catch (tryMS) {
    try {
      request = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (otherMS) {
      try {
        request = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (failed) {
        request = null;
      }
    }
  }	
  return request;
}

window.onload = function(){
	var wid = (screen.width - 300)/2;
	document.getElementById('mensagem').style.left = wid+'px';
	document.getElementById('mensagem').style.top = '140px';
	document.getElementById('mensagem').style.display = 'block';
}

function Fechar(){
	document.getElementById('mensagem').style.display = 'none';
}