title: Sub Option Groups in Bootstrap-Select
body: <p>The <code>select</code> code below is possible <strong>without</strong> using Bootstrap-Select plugin, but not when using it:</p>
  
  <pre><code>&lt;div class="container"&gt;
      &lt;select&gt;
          &lt;optgroup label="Group 1"&gt;
              &lt;optgroup label="Sub Group 1"&gt;
                  &lt;option&gt;Item 1&lt;/option&gt;
                  &lt;option&gt;Item 2&lt;/option&gt;
                  &lt;option&gt;Item 3&lt;/option&gt;
              &lt;/optgroup&gt;
              &lt;option&gt;Item 2&lt;/option&gt;
              &lt;option&gt;Item 3&lt;/option&gt;
          &lt;/optgroup&gt;
          &lt;optgroup label="Group 2"&gt;
              &lt;option&gt;Item 1&lt;/option&gt;
              &lt;option&gt;Item 2&lt;/option&gt;
              &lt;option&gt;Item 3&lt;/option&gt;
          &lt;/optgroup&gt;
      &lt;/select&gt;
  &lt;/diV&gt;​
  </code></pre>
  
  <p>How can I use subgroups (nested optiongroups) using this <a href="http://silviomoreto.github.io/bootstrap-select/" rel="noreferrer">plugin</a>?</p>
  
  <p>The first option group is not shown if I use nested. Only the second (children) optgroup and its options.</p>
  
  <p>Here is the plugin website:
  <a href="http://silviomoreto.github.io/bootstrap-select/" rel="noreferrer">http://silviomoreto.github.io/bootstrap-select/</a></p>