title: How to achieve nested lists with rubaxa sortable.js
body: <p>I'm using Rubaxas Sortable.js to be able to sort lists.</p>
  
  <p>My problem is that i can only move the ".group_container" to the bottom of the main holder but not inbetween the other lists.</p>
  
  <p>Heres a jsFiddle  <a href="https://jsfiddle.net/adishardis/6csou39n/4/" rel="noreferrer">https://jsfiddle.net/adishardis/6csou39n/4/</a> </p>
  
  <pre><code>&lt;h1&gt;Sortable&lt;/h1&gt;
  
  &lt;div class="group" id="main"&gt;
    &lt;div class="group group_container" id="group1"&gt;
      a
      &lt;div class="question"&gt;item 1&lt;/div&gt;
      &lt;div class="question"&gt;item 2&lt;/div&gt;
      &lt;div class="question"&gt;item 3&lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="group group_container" id="group2"&gt;
      b
      &lt;div class="question"&gt;item 4&lt;/div&gt;
      &lt;div class="question"&gt;item 5&lt;/div&gt;
      &lt;div class="question"&gt;item 6&lt;/div&gt;
    &lt;/div&gt;
    &lt;div class="group group_container" id="group3"&gt;
      c
      &lt;div class="question"&gt;item 7&lt;/div&gt;
      &lt;div class="question"&gt;item 8&lt;/div&gt;
      &lt;div class="question"&gt;item 9&lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>What am I missing?</p>