### Please provide a brief summary of the bug

When a JSplitPane is embedded inside a lazily-initialized panel, and this panel is displayed using a dialog created via JOptionPane.createDialog(), the divider location is not preserved when reopening the dialog. This is a regression observed in OpenJDK 24. The issue does not occur in OpenJDK 23, where the divider location remains as the user left it.

### Did you test with the latest update version?

- [x] Yes alos tested with 24.0.1

### Please provide steps to reproduce where possible

Steps to Reproduce:
- Run the test case below
- Click "Open Dialog"
- Move the JSplitPane divider to a different location
- Close the dialog
- Click "Open Dialog" again
- The divider is reset to a new location and does not retain the previous position

### Test Case

<details>
<summary>SplitPaneResetBugOptionPane.java (click to expand)</summary>

```java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;

/**
 * Reproduces a regression in OpenJDK 24:
 * JSplitPane loses divider location when reopened via JOptionPane.createDialog().
 *
 * On OpenJDK 23: divider location is preserved across dialog openings.
 * On OpenJDK 24: divider location is lost and resets on each reopening.
 */
public class SplitPaneResetBugOptionPane {

    private static JPanel lazyPanel;
    private static JSplitPane splitPane;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(SplitPaneResetBugOptionPane::createAndShowUI);
    }

    private static void createAndShowUI() {
        JFrame frame = new JFrame("JSplitPane Divider Location");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton openDialogButton = new JButton(new AbstractAction("Open Dialog") {
            @Override
            public void actionPerformed(ActionEvent e) {
                openDialogFromOptionPane(frame);
            }
        });

        frame.getContentPane().add(openDialogButton, BorderLayout.CENTER);
        frame.setSize(400, 100);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    private static void openDialogFromOptionPane(JFrame parent) {
        if (lazyPanel == null) {
            System.out.println("Creating lazy panel...");
            lazyPanel = new JPanel(new BorderLayout());

            JPanel left = new JPanel();
            left.setBackground(Color.ORANGE);
            JPanel right = new JPanel();
            right.setBackground(Color.LIGHT_GRAY);

            splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right);
            splitPane.setPreferredSize(new Dimension(400, 200));

            // Set initial divider location — not preserved across dialog openings in OpenJDK 24
            splitPane.setDividerLocation(120);

            lazyPanel.add(splitPane, BorderLayout.CENTER);
        }

        JOptionPane optionPane = new JOptionPane(lazyPanel, JOptionPane.PLAIN_MESSAGE, JOptionPane.DEFAULT_OPTION);
        JDialog dialog = optionPane.createDialog(parent, "SplitPane Dialog (JOptionPane)");
        dialog.setModal(true);
        dialog.setVisible(true);
    }
}
```

### Expected Results

When reopening the dialog, the divider location should remain where the user left it.


### Actual Results

Each time the dialog is reopened, the JSplitPane resets to a new divider location, discarding the previous state.

### What Java Version are you using?

openjdk 24 2025-03-18 OpenJDK Runtime Environment Temurin-24+36 (build 24+36) OpenJDK 64-Bit Server VM Temurin-24+36 (build 24+36, mixed mode, sharing)

### What is your operating system and platform?

Windows 10 22H2