I found the answer. Here is one one way to do it.
<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window id="main" title="Konami Browser" width="800" height="600"
xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<browser type="content" src="http://google.com/" flex="1"/>
</window>
Of course the other files in the directory structure are required as well.