Apple uses Prototype and Scriptaculous for that sliding menu. Perhaps you could look at the code and adapt it for mootools? Looks pretty simple:
Code:
var itunesSlider = null;
Event.observe(window, 'load', function() {
var container = $('itunesslider');
itunesSlider = new AC.SlidingBureau(container);
var drawers = $$("#itunesslider .drawers>li");
for (var i = 0; i < drawers.length; i++) {
var handle = drawers[i].getElementsByClassName('drawer-handle')[0];
var content = drawers[i].getElementsByClassName('drawer-content')[0];
var drawer = new AC.SlidingDrawer(content, handle, itunesSlider, {
triggerEvent: 'mouseover', triggerDelay: 120});
itunesSlider.addDrawer(drawer);
}
setTimeout(freeDrawers(container), 1000);
});
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