function hide_overlay() {
  Effect.Fade('tpl-popup', {duration: .3});
  Effect.Fade('tpl-overlay', {from: .6, duration: .5});

}

function display_overlay(target) {
  offset = /*window.pageYOffset + document.body.scrollTop +*/ document.documentElement.scrollTop;
  overlay_offset = (offset > 160) ? offset - 80 : offset / 2;
  $('tpl-overlay').style.top = overlay_offset + 'px';
  $('tpl-popup').style.top = offset + 'px';
  $('tpl-popup').innerHTML = "<div id='tpl-popup-update-message' class='font-clean'><h3>Retrieving Content</h3></div>";

  Effect.Appear('tpl-overlay', {from:0.05, to:.6, duration:.4});
  Effect.Appear('tpl-popup', {duration: .5});

  var ajax = new Ajax.Updater(
            'tpl-popup',
            target, 
            { method: 'post',
              evalScripts: true
              });
}