FULL PRODUCT VERSION :
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows 2000 [Version 5.00.2195], but this bug exists in all Java environments

A DESCRIPTION OF THE PROBLEM :
If a mouseListener is added to the JTabbedPane subcomponents ScrollableTabPanel or ScrollableTabViewport, changing tab using the mouse is impossible when the tabbed pane uses SCROLL_TAB_LAYOUT.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the program below (a.java) using JVM 1.4. Then use any java from 1.4 to run to show that it works. Then use any java from 1.5.0 (beta1,2,rc,or "golden") and you will be able to reproduce the problem.

In the code, you can uncomment 6 lines of code so that the subcomponents to the JTabbedPane ScrollableTabPanel or ScrollableTabViewport are not added for mouse listening. This will make it work in J2SE 5.0 but then no mouseListener is present for those components!

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The JTabbedPane when using SCROLL_TAB_LAYOUT should always accept mouseClick (when tab is enabled/visible) to change tab. This does not work with J2SE 5.0.
ACTUAL -
The JTabbedPane when using SCROLL_TAB_LAYOUT doesn't change tab at mouseClick (when tab is enabled/visible) using J2SE 5.0. This works fine under any Java 1.4.x.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;

public class a
{
  public static void main(String [] args)
    {
    JTabbedPane tp=new JTabbedPane();

    // The line of code below makes mouse action in JTabbedPane not
    // to work, i.e. doesn't change tab when clicked upon...
    tp.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);

    tp.addTab("First",new JPanel());
    tp.addTab("Second",new JPanel());
    tp.addTab("Third",new JPanel());
    tp.addTab("Fourth",new JPanel());
    tp.addTab("Fifth",new JPanel());
    tp.addTab("Sixth",new JPanel());
    tp.addTab("Seventh",new JPanel());

    JFrame f=new JFrame("Scroll tab layout in tabbed pane doesn't work");
    Container c=f.getContentPane();
    c.addContainerListener(new CL());
    c.setLayout(new BorderLayout());
    c.add(tp,BorderLayout.CENTER);
    f.setBounds(0,0,500,300);
    f.setVisible(true);
    }
}

class CL implements ContainerListener
{
  // Dummy mouse listener...
  MouseListener ma=new MouseAdapter()
    {
    public void mousePressed(MouseEvent e)
      {
      if ( !e.isConsumed() && (e.isPopupTrigger()
        || (e.getModifiers()&(InputEvent.BUTTON2_MASK|InputEvent.BUTTON3_MASK))!=0) )
        {
        System.out.println("Mouse button 2 pressed...");
        e.consume();
        }
      }
    };

  public void componentAdded(ContainerEvent e)
    {
    addMouseListener(e.getChild());
    }

  public void componentRemoved(ContainerEvent e)
    {
    removeMouseListener(e.getChild());
    }

  void addMouseListener(Component c)
    {
    // The 6 lines of code below makes sure a mouse listener is not
    // added to the Viewport. Uncomment to verify the problem...
    // String name=c.getClass().getName();
    // System.out.println("...adding mouse listener to "+name);
    // if ( name.endsWith("TabbedPaneUI$ScrollableTabPanel")
    // || name.endsWith("TabbedPaneUI$ScrollableTabViewport") )
    // ; // Don't add mouse listener!
    // else
    c.addMouseListener(ma);

    if ( c instanceof Container )
      {
      Container cn=(Container)c;
      cn.addContainerListener(this);
      Component [] cs=cn.getComponents();
      for ( int ii=cs.length-1; ii>=0; --ii )
        addMouseListener(cs[ii]);
      }
    }

  void removeMouseListener(Component c)
    {
    c.removeMouseListener(ma);

    if ( c instanceof Container )
      {
      Container cn=(Container)c;
      cn.removeContainerListener(this);
      Component [] cs=cn.getComponents();
      for ( int ii=cs.length-1; ii>=0; --ii )
        removeMouseListener(cs[ii]);
      }
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
The reason for having a mouseListener for all components and possibly subcomponents is to be able to track a pop-up menu displayed with mouse button 2. It should always be possible to add a mouseListener to a component without disrupting its functionality, otherwise this component should override addMouseListener to do other things.

The workaround means checking the class name of the components that are to be added for mouse listening and checking if the name is Viewport or Scrollpane subcomponent of the (e.g.) javax.swing.plaf.basic.BasicTabbedPaneUI.

See the code (uncomment 6 lines) for an example.

Release Regression From : 1.4.2
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.
###@###.### 10/19/04 00:17 GMT