title: How do I fade in and out a hidden element using Mootools
body: <p>I am trying to fade in a hidden element, and then fade it back out again using mootools.</p>
  
  <p>I can't just use <code>$('my_div').fade('toggle')</code>, because that assumes the element is always visible, whereas my div starts out with <code>display:none</code>.</p>
  
  <p>Is there a simple way to combine a fade in/out with a slide in/out or some other way to achieve a nice effect?</p>