JTabbedPane fails to clip tab text

I have a JTabbedPane with multiple tabs, using WRAP_TAB_LAYOUT.
When the user shrinks the window, the longest tab label draws its
text outside the tab area instead of clipping it. It even runs
over into the next tab.

Also, when using Numbus LAF, it does not size properly.
What am I missing to get this to work properly?

Here is a short code sample:

import java.awt.BorderLayout;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.UIManager;
import javax.swing.UIManager.LookAndFeelInfo;

public class Tester extends JPanel {

   public Tester() {
      setLayout( new BorderLayout() );
      setBorder( BorderFactory.createEmptyBorder( 10, 10, 10, 10 ) );

      JTabbedPane pane = new JTabbedPane( JTabbedPane.TOP,
                                          JTabbedPane.WRAP_TAB_LAYOUT );
      pane.setBorder( BorderFactory.createEmptyBorder( 10, 10, 10, 10 ) );

      JLabel p1 = new JLabel( "p1" );
      pane.addTab( "this is tab number 1, long label", p1 );
      JLabel p2 = new JLabel( "p2" );
      pane.addTab( "tab number 2", p2 );
      JLabel p3 = new JLabel( "p3" );
      pane.addTab( "this is tab 3", p3 );
      JLabel p4 = new JLabel( "p4" );
      pane.addTab( "tab 4", p4 );
      JLabel p5 = new JLabel( "p5" );
      pane.addTab( "another tab", p5 );

      add( pane, BorderLayout.CENTER );
   }

   public static void main( String[] args ) {
      try {
         for ( LookAndFeelInfo info : UIManager.getInstalledLookAndFeels() ) {
            if ( "Nimbus".equals( info.getName() ) ) {
               UIManager.setLookAndFeel( info.getClassName() );
               break;
            }
         }
      } catch ( Exception e ) {
         System.out.println( "No nimbus found" );
      }

      javax.swing.SwingUtilities.invokeLater( new Runnable() {
         public void run() {
            JFrame frame = new JFrame( "Tester" );
            frame.addWindowListener( new WindowAdapter() {
               @Override
               public void windowClosing( WindowEvent e ) {
                  System.exit( 0 );
               }
            } );

            Tester t = new Tester();
            frame.add( t );
            frame.pack();
            frame.setVisible( true );
         }
      } );
   }
}