Swing Debugging

Kirill Grouchnikov wrote a nice article on the subject of Swing Debugging. This is still a dark area for newcomers to Swing application development. Blocking the EDT (Event Dispatch Thread) or updating Swing components off the EDT are common problem areas for newcomers and contribute to the fact that people think that Swing is crapy or slow.
Fortunately some people have contributed tools to verify against these violations, you can find 2 classes for debugging Swing here (CheckThreadViolationRepaintManager and EventDispatchThreadHangMonitor).