Why Does My Java Swing Wait Cursor Not Always Display Correctly, and How Can I Fix It Using the Glass Pane?

Issue: Wait Cursor Display Problem in Java

In the Java Swing library, setting the cursor for a component doesn't always take effect when there are nested panels with custom cursors. This can lead to inconsistencies in cursor behavior, where the wait cursor is not displayed as expected.

Fix: Utilizing Glass Pane for Cursor Control

To address this issue, it's recommended to manage the cursor display using the glass pane of the frame that contains the components. The glass pane is a transparent pane that sits at the top-level of the frame's hierarchy. By setting the cursor on the glass pane, any component within the frame can display the wait cursor regardless of their own cursor settings.

Modified Code Solution:

The following modified code demonstrates how to use the glass pane for wait cursor display:

import java.awt.*;
import java.awt.event.*;
import java.util.TimerTask;
import java.util.Timer;

public class BusyCursorTest extends javax.swing.JFrame {

    private javax.swing.JPanel cursorPanel = null;

    public BusyCursorTest() {

        // ...

        public static void startWaitCursor(javax.swing.JFrame frame) {
            frame.getGlassPane().setCursor(java.awt.Cursor.getPredefinedCursor(java.awt.Cursor.WAIT_CURSOR));
            frame.getGlassPane().addMouseListener(mouseAdapter);
            frame.getGlassPane().setVisible(true);
        }

        private static void stopWaitCursor(javax.swing.JFrame frame) {
            frame.getGlassPane().setCursor(originalCursor);
            frame.getGlassPane().removeMouseListener(mouseAdapter);
            frame.getGlassPane().setVisible(false);
        }

        // ...
    }

    // ...

    public static java.awt.Cursor originalCursor = null;

    private static final java.awt.event.MouseAdapter mouseAdapter = new java.awt.event.MouseAdapter() {
    };

    public static final int DELAY_MS = 250;
}

In this modified code, the startWaitCursor() and stopWaitCursor() methods are used to manage the cursor on the frame's glass pane. This ensures that the wait cursor is consistently displayed regardless of the cursor settings of the nested components.

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