It's the line where you say:
frame.setContentPane( new StreamGUI() );
Your StreamGUI class is a frame itself, so
you should use it as a one. You don't need to call setContentPane() because the content's were already set in it's constructor. As for the error, it's because you're trying to add a JFrame to a JFrame, you can only add a Container as the contents of a JFrame.
Jeff
[ April 14, 2002: Message edited by: Jeff Smith ]