FULL PRODUCT VERSION :
java version "1.6.0_02"
Java(TM) SE Runtime Environment (build 1.6.0_02-b06)
Java HotSpot(TM) Client VM (build 1.6.0_02-b06, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
This appears to be a regression issue in 1.6 almost exactly similar to a bug
previously reported and marked closed as of 1.3:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4143929,
This bug appears to have resurfaced in 1.6. The problem is that the combobox
cell editor does not disappear properly when the same value as is currently
selected in the combo box is selected again from the combobox's popup.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Compile and run the program given below under jdk 1.6
2) Click the cell and select a value. Note that the editor disappears.
3) Click the cell and select a different value. Note that the editor disappears.
4) Click the cell and select the same value. Note that the editor does not
disappear. This is the regression bug. It did disappear in 1.4.2 and 1.5.
5) Click the cell, then click the body of the table outside the popup. Note that
the editor disappears. This seems like it is the correct behavior, but it is a
regression issue, as under 1.4.2 and 1.5, the editor does _not_ disappear.

You can compile the program with 1.4.2 javac and run the program with the
java from 1.4.2, 1.5 and 1.6 to see the differing behavior, or you can compile
with the javac from each version -- the differing behavior remains.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expected the program to work the same under 1.6 as it does under 1.5 and
1.4.2, that is, the editor would disappear when the same value was selected.
ACTUAL -
The program does not work the same under 1.6 as it does under 1.4.2 and 1.5.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------

import javax.swing.*;
import java.awt.*;

public class ComboBoxEditorBug {
	public ComboBoxEditorBug() {
		MyFrame mf = new MyFrame();
		mf.setSize( 200, 200 );
		mf.setVisible( true );
	}

	public static void main( String args[] ) {
		SwingUtilities.invokeLater( new Runnable() {
			public void run() { new ComboBoxEditorBug(); }
		} );
	}

	public class MyFrame extends JFrame {
		public MyFrame() {
			setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			JPanel contentPane = (JPanel) getContentPane();
			contentPane.setLayout( new BorderLayout() );

			final JTable table = new JTable( 1, 1 );
			JComboBox combo = new JComboBox();
			combo.addItem( "Item 1" );
			combo.addItem( "Item 2" );
			combo.addItem( "Item 3" );
			combo.addItem( "Item 4" );

// Uncomment this code for the workaround
//			combo.addPopupMenuListener( new PopupMenuListener() {
//				public void popupMenuWillBecomeVisible( PopupMenuEvent e ) {}
//				public void popupMenuWillBecomeInvisible( PopupMenuEvent e ) {
//				TableCellEditor editor = table.getCellEditor();
//				if ( editor != null )
//					editor.stopCellEditing();
//				}
//				public void popupMenuCanceled( PopupMenuEvent e ) {}
//			});


			table.getColumnModel().getColumn( 0 ).setCellEditor( new DefaultCellEditor( combo ) );

			contentPane.add( "Center", table );
		}

	}
}

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

CUSTOMER SUBMITTED WORKAROUND :
Adding a popup menu listener which stops editing; this is the commented
code in the example. This causes the editor to not be displayed in step 4
when running java 1.6. It also causes the editor to not be displayed in step
5 under 1.4.2 and 1.5.

Release Regression From : 5.0u12
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.