While running a Swing app, type Ctrl-\ to get a stack trace of each thread.

To change the look and feel on the command line to Windows (only works on Windows) or GTK (a native look on Linux) use the following:

java -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel MyApp

java -Dswing.defaultlaf=com.sun.java.swing.plaf.windows.WindowsLookAndFeel MyApp