frameset-child.html

<!DOCTYPE html PUBLIC "-//IETF//DTD HTML//EN">
<html><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
      <script>
      addEventListener("click", function() {
        window.parent.postMessage("CLICK", "*");
      });
    </script>
    <style>
      html {
        background-color: green;
      }
    </style>
</head>
<body>
   Resizable When Green - Click to toggle
</body>
</html>