<?xml version="1.0" encoding="utf-8"?>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>History navigation during drag and drop: helper file</title>
<style type="text/css">
div[ondragenter]
  {margin:200px 0 0 200px;
  width:200px;
  height:100px;
  color:white;
  background-color:navy;}
div[ondragenter]:before
  {display:block;
  content:"";
  border-style:solid;
  position:relative;
  top:-50px;
  left:-200px;
  border-width:100px;
  border-color:transparent navy transparent transparent;}
</style>
</head>
<body>
<p>Drag box to the blue arrow but don't drop it yet. You should be returned back to start page.</p>
<div ondragenter="event.preventDefault()" ondragover="history.go(-1)"/>
</body>
</html>