1. Start SwingSet2 via the Terminal / Command line.
2. Open the JTable page in the SwingSet2 application.
3. Set the focus on a table cell (or click on a table cell).
4. Press Ctrl+F1 (show/hide tooltip) on a cell of JTable in SwingSet2, then the following NullpointerException is seen (e.g. when running on Windows)

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "java.awt.event.MouseEvent.getLocationOnScreen()" because "this.mouseEvent" is null
        at java.desktop/javax.swing.ToolTipManager.showTipWindow(ToolTipManager.java:273)
        at java.desktop/javax.swing.ToolTipManager.show(ToolTipManager.java:876)
        at java.desktop/javax.swing.ToolTipManager$AccessibilityKeyListener.keyPressed(ToolTipManager.java:912)
        at java.desktop/java.awt.Component.processKeyEvent(Component.java:6584)
        at java.desktop/javax.swing.JComponent.processKeyEvent(JComponent.java:2896)
        at java.desktop/java.awt.Component.processEvent(Component.java:6403)
        at java.desktop/java.awt.Container.processEvent(Container.java:2266)
        at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001)
        at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
        at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
        at java.desktop/java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1952)
        at java.desktop/java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:883)
        at java.desktop/java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1150)
        at java.desktop/java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:1020)
        at java.desktop/java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:848)
        at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4882)
        at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
        at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
        at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
        at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:775)
        at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
        at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
        at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
        at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
        at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:747)
        at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
        at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
        at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:744)
        at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
        at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
        at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
        at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
        at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
        at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

This was observed with OpenJDK 17.0.10 and 22+36 .