Run the attached test case. It shows a frame with a couple of components in it: several Labels and a single TextField. The frame has a WindowListener added, so when user closes the frame, it is disposed, and the whole JVM must terminate. However, after the frame is closed, the application is not terminated.
If the TextField is removed from the test, it operates successfully. Swing JTextFields also don't cause any problems. The bug is reproducible at least on Linux and Solaris with 6.0-fcs and 7.0-b11. Thread dump at the moment of freeze is also attached.