How can I include a dropdown in menu_local_tasks tabs? I am trying to include a Bootstrap style dropdown in the local_tasks tabs on a section of my website. I thought I might be able to accomplish this with the 'theme callback' option of 'HOOK_MENU', but it doesn't run the custom callback. Any ideas on a good way to accomplish this?
Menu:
    $items['module/submenu/tab'] = array(
    'title' =&gt; 'Title',
    'page callback' =&gt; 'mymodule_menu_callback',
    'access arguments' =&gt; array('access content'),
    'theme callback' =&gt; 'mymodule_menu_local_task_dropdown',
    'type' =&gt; MENU_LOCAL_TASK,
);

Callback:
function mymodule_menu_local_task_dropdown($variables) {
 $link = $variables['element']['#link'];
 $link_text = $link['title'];
 $classes = array();

 if (!empty($variables['element']['#active'])) {
 // Add text to indicate active tab for non-visual users.
 $active = '&lt;span class=&quot;element-invisible&quot;&gt;' . t('(active tab)') . '&lt;/span&gt;';

 // If the link does not contain HTML already, check_plain() it now.
 // After we set 'html'=TRUE the link will not be sanitized by l().
 if (empty($link['localized_options']['html'])) {
  $link['title'] = check_plain($link['title']);
 }
 $link['localized_options']['html'] = TRUE;
 $link_text = t('!local-task-title!active', array('!local-task-title' =&gt; $link['title'], '!active' =&gt; $active));

 $classes[] = 'active';
}

$classes[] = 'dropdown';

//haven't written this part yet
$dropdown = 'build dropdown';

return '&lt;li class=&quot;' . implode(' ', $classes) . '&quot;&gt;' . l($link_text, $link['href'], $link['localized_options']) . $dropdown . &quot;&lt;/li&gt;\n&quot;;
}

What I'm looking for:
For the drop-down menu you need include drop-down JavaScript in the "page callback". See drupal_add_library() function.

And I recommend for you pay attention to "CTools module".

"Drop-Down Menu" Code from CTools module:

  // Show examples of ctools javascript widgets
  $output .= '&lt;h2&gt;' . t('CTools Javascript Widgets') . '&lt;/h2&gt;';

  // Create a drop down menu
  $links = array();
  $links[] = array(
    'title' =&gt; t('Link 1'),
    'href' =&gt; $_GET['q'],
  );
  $links[] = array(
    'title' =&gt; t('Link 2'),
    'href' =&gt; $_GET['q'],
  );
  $links[] = array(
    'title' =&gt; t('Link 3'),
    'href' =&gt; $_GET['q'],
  );

  $output .= '&lt;h3&gt;' . t('Drop Down Menu') . '&lt;/h3&gt;';
  $output .= theme('ctools_dropdown', array('title' =&gt; t('Click to Drop Down'), 'links' =&gt; $links));