<!DOCTYPE html>
<html>
<head>
  <script type="text/javascript">
    function doTest()
    {
      var editor = document.getElementById("editor");
      document.getSelection().selectAllChildren(document.body);
    }
  </script>
</head>
<body onload="doTest();">
<p>normal text</p>
<div id="editor">editable text</div>
</body>
</html>