ADDITIONAL SYSTEM INFORMATION :
Mac OS Big Sur

A DESCRIPTION OF THE PROBLEM :
On the latest Mac OS Big Sur I have a Swing frame which shows a Swing Dialog. If I switch the Swing frame to full screen and then show the dialog, the dialog is also full screen and the user interface freezes.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Show a Swing frame, maximize it to full screen, from the frame show a dialog.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Showing the dialog should not freeze the entire application.
ACTUAL -
I can no longer close the dialog or switch to the main frame.

---------- BEGIN SOURCE ----------
    JFrame fr = new JFrame("abc");
    fr.setSize(500, 500);
    fr.getContentPane().add(new JButton(new AbstractAction("TEST") {
      
      @Override
      public void actionPerformed(ActionEvent e) {
        JDialog dlg = new JDialog(fr, false);
        dlg.setSize(500, 500);
        dlg.getContentPane().add(new JTextArea());
        dlg.setVisible(true);
      }
    }));
    fr.setVisible(true);
  }
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Unfortunately the method "com.apple.eawt.FullScreenUtilities.setWindowCanFullScreen" does not seem to work anymore so the only workaround I have is to set the entire frame as not resizable: frame.setResizable(false);

FREQUENCY : always