 e.dataTransfer.effectAllowed = 'all';
  };
  blue.ondragenter = blue.ondragover = function (e) {
    e.preventDefault();
  };
  blue.ondragleave = function (e) {
    alert('Release the mouse over this dialog');
  };
};
</script>
<div draggable="true"></div>
<div></div>

<ol>
  <li>Drag the orange square over the blue square, then back over the orange square.</li>
  <li>An alert may appear - release the mouse over the dialog. Dismiss it (you may need to use keyboard or mouse gestures such as gesture-down,ge