Mine

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        id="win"
        title="Test"
        orient="horizontal"
>
	<vbox>
	   <textbox id="test1" value="one" collapsed="true" />
	   <textbox id="test2" value="two" />
	   <button oncommand="alert(document.getElementById('test1').value);alert(document.getElementById('test2').value);" />
	</vbox>
</window>