🚀 go-pugleaf

I you have a JOptionPane with a JButton and a JLabel, in the event handler
of the JButton I do a label.setText("very long text,.. blah etc").
When I click the button I would expect the JOptionPane to resize so that the
JLabel shows the whole text, but that does not happen. I found out that The
label doesn't show anything when the length of the text exceeds a certain
value. How can you force the JOptionPane to recalculate its layout?

Here is my test program:
public class TestPanel extends JPanel {
        JButton button = new JButton("pack");
        JLabel label = new JLabel("");
        StringBuffer sb = new StringBuffer();
        
        public TestPanel() {
                add(button);
                add(label);
                button.addActionListener(new ActionListener() {

                
                public void actionPerformed(ActionEvent actionEvent) {
                        //label.setText("kfhnwqeiv jglsgjdsfl; mgldsfmgdsf ,gmns;lfg
gfegvnjeqrp");
                        sb.append("aap");
                        label.setText(sb.toString());   
                

                        }

                
        });
        }
        public static void main(String[] args) {

                        javax.swing.SwingUtilities.invokeLater(new Runnable() {
                                public void run() {
                                        createAndShowGUI();
                                }
                        });
                }
                
        private static void createAndShowGUI() {
                        
                TestPanel tp = new TestPanel();
                                JOptionPane.showConfirmDialog(null, tp, "Set datafile",
JOptionPane.OK_CANCEL_OPTION, -1, null);
        
        }
}