title: dat.gui not rendering properly in WebGL window
body: <p>When i try to render my dat.gui with a button and a textbox on top of my WebGL window i get this:</p>
  
  <p><a href="https://i.stack.imgur.com/N9peP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/N9peP.png" alt="The button and the textbox is not showing"></a></p>
  
  <p>The "Close Controls" part of the dat.gui is showing, but for some reason my button and textbox is not. I use three.js to create the WebGL window.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>function ini()
  {
      this.button1 = function () { alert("HEJ"); };
      this.text1 = "Hallo World";
  }
  
  var gui = new dat.GUI({ autoPlace: false });
  var div = document.getElementById('datGui');
  div.appendChild(gui.domElement);
  var i = new ini();
  gui.add(i, "button1");
  gui.add(i, "text1");</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="datGui"&gt;
   &lt;canvas id="canvas" style="position: absolute; background-color: black; width: auto; "&gt;&lt;/canvas&gt; 
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>