The lookandfeel package is not copied into the jar. So neither Default.glf or DefaultLookAndFeel.png are included and the widget example crash.
Now I can easily fix it via the build.xml, I am however unsure of how I should do it. I am unfamiliar with your policy about people checking in and out stuff on your CVS server.
Just post you changes in the User Code forum, and someone will look at them and check them in.