title: firefox bug - Options disappeared on hover
body: <p>Firefox represents a bug when I insert a select box on mouseenter event. The whole dropdown list is gone on hover. How can I fix this bug?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>document.querySelector('#test').addEventListener('mouseenter',function(){
      this.innerHTML = '&lt;select&gt;&lt;option value=1&gt;2&lt;/option&gt;&lt;option value=2&gt;3&lt;/option&gt;&lt;/select&gt;';
  });</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>#test{
      width: 100px;
      height: 100px;
      background-color: #000;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="test"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>