function openMain(url) {
  width = 804;
  height = 482;

  if(navigator.appName == "Microsoft Internet Explorer") {
    posX = (window.screen.availWidth / 2) - (width / 2);
    posY = (window.screen.availHeight / 2) - (height / 2);
    window.open(url,"","width=" + width + ",height=" + height + ",left=" + posX + ",top=" + posY + ",menubar=no,scrollbars=no");
  } else {
    posX = (screen.width / 2) - (width / 2);
    posY = (screen.height / 2) - (height / 2);

    window.open(url,"main","width=" + width + ",height=" + height + ",screenX=" + posX + ",screenY=" + posY + ",menubar=no,scrollbars=no");
  }
}