function openWindow (page) {
 x = (640 - 490) / 2;
 y = (480 - 430) / 2;

 if (screen) {
  x = (screen.availWidth - 490) / 2;
  y = (screen.availHeight - 430) / 2;
 }

 if (! page) {
  page = '/key.htm';
 }

 window.open (page, 'key', 'width=490,height=430,screenX='+x+',screenY='+y+',top='+y+',left='+x+',directories=no,location=no,menubar=no,scrollbars=no,status=no,toolbar=no,resizable=no,scrolling=no');
}