//POPUP PADRÃO
function popup(pagina,largura,altura,rolagem){
  var posX;
  var posY;
  posX = (window.screen.width - largura) / 2;
  posY = (window.screen.height - altura) / 2;
  var win = window.open(pagina,"_blank","width=" + largura + ", height=" + altura + ", top=" + posY + ", left=" + posX + ", scrollbars=" + rolagem);
  win.focus();
}