function popup (url, nome, largura, altura, posicao, recize, barras) {
  if (posicao == 0) {
    posleft = 20;
    postop  = (screen.height) ? (screen.height - altura) / 2 - 50 : 100;
  } 
  else if (posicao == 1) {
    posleft = (screen.width) ? (screen.width - largura) / 2 : 100;
   postop  = (screen.height) ? (screen.height - altura) / 2 - 50 : 100;
  } 
  else if (posicao == 2) {
    posleft = (screen.width) ? (screen.width - largura) - 28 : 100;
    postop  = (screen.height) ? (screen.height - altura) / 2 - 50 : 100;
  }
  opBarras = (barras) ? "yes" : "no";
  opRecize = (recize) ? "yes" : "no";

  settings = 'width=' + largura + ', height=' + altura + ', top=' + postop + ', left=' + posleft + ', scrollbars=' + opBarras + ', location=no, directories=no, status=no, menubar=no, toolbar=no, resizable=' + opRecize;
  window.open(url, nome, settings);
}

function abre_seguranca() {
  popup ("http://www.shopdelivery.com.br/bancodeimagens/comodo/selo_seguranca.html", "seguranca", 450, 350, 1, false, false);
}