<!doctype html>
<html>
  <head>
    <title>Button inside draggable element</title>
    <style type="text/css">
button { border: 1px solid orange; border-top-width: 20px; }
    </style>
    <script type="text/javascript">
window.onload = function () {
  document.getElementsByTagName('div')[0].ondragstart = function (e) {
    e.dataTransfer.effectAllowed = 'copy';
    e.dataTransfer.setData('Text', 'dummy text');
  };
};
    </script>
  </head>
  <body>

    <p>Press your mouse button down on the orange block and drag downwards. It should <strong>not</strong> drag the block or text.</p>
    <div draggable="true">
      <button>Dummy text</button>
    </div>

  </body>
</html>