<!DOCTYPE html>
<html>
<head>
  <script type="text/javascript">
    function doTest()
    {
      document.getSelection().selectAllChildren(document.body);
      var editor = document.getElementById("editor");
      editor.focus();
      editor.selectionStart = 2;
      editor.selectionEnd = 4;
      editor.blur();
      editor.focus();
    }
  </script>
</head>
<body onload="doTest()">
<p>normal text</p>
<textarea id="editor">textarea</textarea>
</body>
</html>