"Substitutions" fieldset does not behave like it should.

When I use the Rubik admin theme, the substitutions fieldset is acting very strange.

First it shows all the data inside of it, then I have to click twise do get it to collapse.

I think that this is because its a hard coded fieldset in the #prefix.

// We have to create a manual fieldset because fieldsets do not support IDs.
      // Use 'hidden' instead of 'markup' so that the process will run.
      // Add js for collapsible fieldsets manually
      drupal_add_js('misc/collapse.js');
      $form['display_title']['contexts_prefix'] = array(
        '#type' => 'hidden',
        '#id' => 'edit-display-substitutions',
        '#prefix' => '<div><fieldset id="edit-display-substitutions" class="collapsed collapsible"><legend>' . t('Substitutions') . '</legend>',
        '#process' => array('ctools_dependent_process'),
        '#dependency' => array('edit-display-title-hide-title' => array(PANELS_TITLE_FIXED)),
      );

The comment says We have to create a manual fieldset because fieldsets do not support IDs.
And as far as I can see, thats not true.
You can specify #attributes with "ID" => "edit-display-substitutions".

My suggestion is this.

Make an array that contains the fieldset

$display_fieldset = array(
        '#title' => t('Substitutions'),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
        '#attributes' => array('id' => 'edit-display-substitutions'),
        '#children' => theme('table', $header, $rows),
      );

And run this thru theme_fieldset

Also, no sure why the type for $form['display_title']['contexts_prefix'] is "hidden"