The JInternalFrame.dispose() method calls the INTERNAL_FRAME_CLOSING
as seen below from swing 1.1beta3 source below -

/*
 * @(#)JInternalFrame.java 1.79 98/08/31
 *
 */

    /**
     * Disposes of this internal frame. If the frame is not already
     * closed, a frame-closing event is posted.
     */
    public void dispose() {
        if (isVisible()) {
            setVisible(false);
        }
        if (isSelected()) {
            try {
                setSelected(false);
            } catch (PropertyVetoException pve) {}
        }
        if (!isClosed) {
          fireInternalFrameEvent(InternalFrameEvent.INTERNAL_FRAME_CLOSING);
          fireInternalFrameEvent(InternalFrameEvent.INTERNAL_FRAME_CLOSED);
        }
    }

In case of java.awt.Frame only WINDOW_CLOSED is fired.
See attached example.

This causes an infinite loop because I am calling iFrame.dispose()
in the INTERNAL_FRAME_CLOSING handler.

sandip.chitale@Eng 1998-10-19