chrome.manifest

content narwhal-xpc content/
resource narwhal-xpc resources/

content narwhal narwhal/

skin narwhal-xpc classic/1.0 skin/classic/

directory structure

 $ find .
.
./extensions
./defaults
./defaults/preferences
./defaults/preferences/debug.js
./defaults/preferences/prefs.js
./chrome
./chrome/chrome.manifest
./chrome/skin
./chrome/skin/classic
./chrome/skin/classic/main.css
./chrome/content
./chrome/content/main.js
./chrome/content/main.xul
./chrome/narwhal
./chrome/resources
./application.ini
./updates
./updates/0
./.xuldev
./components

main.xul

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://narwhal-xpc/skin/main.css" type="text/css"?>

<window id="main" title="Narwhal on XUL" width="300" height="300"
  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">

  <script type="application/javascript" src="chrome://narwhal/content/platforms/xpc/bootstrap.js" />

  <vbox flex='1'>
    <button label="Hello World" oncommand="alert(42);"/>
  </vbox>

</window>