var compute_centered_window_options = function(width, height) {
  var left = parseInt((screen.availWidth/2) - (width/2));
  var top = parseInt((screen.availHeight/2) - (height/2));
  return "width=" + width + ",height=" + height + ",left=" + left + ",top=" + top + ",screenX=" + left + ",screenY=" + top;
};

var open_inline_popup = function(url) {
  window.open(url, 'inlinepopup',
              compute_centered_window_options(780, 500) +
              ',toolbar=no,location=yes,directories=no,status=yes,' +
              'menubar=no,scrollbars=yes,copyhistory=no,resizable=yes');
};