<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin" type="text/css"?>

<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
	orient="vertical">
<label value="The iframe below should show the string 'Here'"/>
<iframe src="data:application/vnd.mozilla.xul+xml,&lt;window xmlns='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'&gt;&lt;label value='Here'/&gt;&lt;/window&gt;"></iframe>
</window>