The testcase in attachment (classes BUG15, CheckBugList, CheckListCellRenderer, CheckListener InstallData) has been extracted from a Sun internal application (openduty2) There is a JPanel added to the JMenu which has been created because it was needed a scrollbar to handle the long list of selectable items (support queues) loaded by the application
The application (openduty2) and the testcase BUG15 perfectly runs with 1.3.x and 1.4.x, but do not work with tiger beta2:

- cannot select more than one item
- cannot scroll
- cannot use buttons to execute any action

In the panel there is a long list of items which are support queues to be selected (in the testcase the list is simply long enought to have an automatic scrollbar, but in the real application it is often longer)
In the attached Screenshot.png you see the original application openduty2 (using acqua Theme) with some queues selected and the same panel in the testcase without any JCheckBox selected

The behaviour changes for check boxes and scroll pane using shift key while selecting or scrolling, but listeners do not receive any JButton action
To verify this behaviour instead of using only the mouse to click on JCheckBox,JButton and scrollbar, use SHIFTKey+MouseClick together on JCheckBox and on the arrows of the scrollbar (dragging scrollbar does not work)
Using SHIFTKey+MouseClick I can select more than one JCheckBox and use the scrollbar arrows: the JScrollPane perfectly moves.
The JButton(s) still do not work even with a SHIFTKey+MouseClick

The behaviour changes for check boxes if the opened JPanel is detached from the application (this is not possible in 1.4.x, but can be done in this testcase using 1.3.1) but JButton still do not work as expected
To verify this behaviour simply move the JPanel which can float in 1.5.0-beta2 in your desktop because, because it is no more linked to the JMenu ( is a new window) See the Screenshot.png where I've moved the panel in the testcase, but I cannot do that in the application when running with 1.4.2_0x, because it is attached to the JMenuBar. 

The look and feel is different using 1.3.x, 1.4.x and 1.5

The problems has been verified on Sol8 and Sol9 with gnome and CDE using java 1.5.0-beta2-b48, simply running: /usr/jdk/j2sdk1.5.0/bin/java -jar BUG15.jar
To run it with 1.3 you need to recompile the classes (see build13 script)