Have extends some UI Components to add additonal features. With the Nimbus L&F
the BaseUI is not working in all cases. See the exception below.
we does not have control over the L&F and this will be a fatal for our customers.
This must be fix in the BaseUI classes or in the Nimbus L&F defintion.
Because the problem occur inside of the Sun classes it is inpossible to compensate it.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.plaf.basic.BasicTabbedPaneUI.rotateInsets(BasicTabbedPaneUI.java:2124)
        at javax.swing.plaf.basic.BasicTabbedPaneUI.getTabAreaInsets(BasicTabbedPaneUI.java:1783)
        at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.calculateTabRects(BasicTabbedPaneUI.java:2528)
        at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.calculateLayoutInfo(BasicTabbedPaneUI.java:2488)
        at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.layoutContainer(BasicTabbedPaneUI.java:2383)
        at java.awt.Container.layout(Container.java:1432)
        at java.awt.Container.doLayout(Container.java:1421)
        at java.awt.Container.validateTree(Container.java:1519)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validateTree(Container.java:1526)
        at java.awt.Container.validate(Container.java:1491)
        at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:670)
        at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:127)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)


Here is the test case for the BasicTabbedPaneUI. The tests for the other basic UI classes are equals.

import java.awt.Container;
import javax.swing.*;
import javax.swing.plaf.basic.*;

public class TestNimbus {

    public static void main( String[] args ) throws Exception{
        UIManager.setLookAndFeel( "sun.swing.plaf.nimbus.NimbusLookAndFeel" );
        JFrame frame = new JFrame();
        Container cont = frame.getContentPane();
        JTabbedPane tab = new JTabbedPane();
        tab.setUI( new BasicTabbedPaneUI() );
        cont.add( tab );
       
        frame.pack();
        frame.show();

    }

}