I use the jQuery SelectBox Plugin for a select box in a hidden DIV container. The problem was that after removing the hidden CSS class from the container, the jQuery SelectBox was empty. I thought that maybe it is in correlation with this statement from A Beautiful Site:

Since the original controls aren’t destroyed (they’re hidden), you can easily integrate this plugin into just about any existing form.

so the only way to get the SelectBox filled correctly was to first destroy  and then reinitialize it (see the code snippet below).

<style>

.hidden {
  display: none;
}

</style>

<script>
$(document).ready(function() {

  $('#show').bind("click", function(){

     $('#container').removeClass('hidden');
     $("#container select").selectBox('destroy');
     $("#container select").selectBox();

  });

  $("select").selectBox();

});
</script>

<a id="show" href="#">show</a>

<div id="container" class="hidden">
  <select>...</select>
</div>