JBuilder 6 Personal ships without Borland's libs, including their custom layout managers. But these layout managers appear in the dropdown list in the designer, fooling people into believing they can be used.

Solution: Instead of using XYLayout, use null as layout, it should have the same effect. And avoid using any layout manager in that list that you don't recognize as part of the "core" JRE.

Or buy Pro or Enterprise, which has the classes. :-)