<?xml version="1.0"?>
<?xul-overlay href="extA1.xul"?>
<?xul-overlay href="extB1.xul"?>
<?xul-overlay href="extA2.xul"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<vbox id="browser-bottombox">
</vbox>
</window>