title: html5 on drag change dragging image or icon
body: <p>I have a simple html like:</p>
  
  <pre><code>&lt;!DOCTYPE HTML&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;style&gt;
      .drag-icon{height: 100px; width: 100px; background-color: red}
  &lt;/style&gt;
  &lt;script&gt;
      function drag(ev) {
          var drag_icon = document.createElement("div")
          drag_icon.className = "drag-icon"
  
          ev.dataTransfer.setData("text/html", drag_icon);
      }
  &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div style="height: 100px; width: 100px; background-color: #CCC" draggable="true" ondragstart="drag(event)"&gt;
          Hellooww world
      &lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Here when I drag the div, while dragging my div is being dragged.
  What I want is when I drag the div the dragging div should be changed to <code>drag_icon</code>.</p>
  
  <p>How can I do this ? </p>