<html>
<head>
<script>

function boom()
{
  var fragEl = document.createElement("span");
  fragEl.setAttribute("contenteditable", "true");
  fragEl.setAttribute("style", "position: absolute;");

  var frag = document.createDocumentFragment();
  frag.appendChild(fragEl);

  window.getSelection().selectAllChildren(fragEl);
}

</script>
</head>

<body contenteditable="true" onload="boom();"></body>
</html>