<html contenteditable="true" xmlns="http://www.w3.org/1999/xhtml"><head><script>

function boom()
{
  document.execCommand("selectAll", false, "");
  try { document.execCommand("justifyfull", false, null); } catch(e) { }
  try { document.execCommand("inserthorizontalrule", false, "false"); } catch(e) { }
  document.execCommand("delete", false, null);
}

</script></head>x y z<body onload="boom();"><div/></body></html>