This is related to CR 6839999 (Cumulative fix for 6762511 and 6838003).
When I executed the tests Test.java and SampleTest.java on Ubuntu I got the actual results mentioned in the CR 6839999 instead of the expected results.

The first 3 buttons are enabled and the 'Test TRANSLUCENT' button is not
The 'Output Graphics Configurations' button outputs:
X11GraphicsConfig[dev=X11GraphicsDevice[screen=0],vis=0x21] is Translucency Capable: false
X11GraphicsConfig[dev=X11GraphicsDevice[screen=0],vis=0x5c] is Translucency Capable: true

Also I have attached the screenshot of what I am seeing.
I also ran the below command before executing the testcase.
gconftool-2 --type bool --set /apps/metacity/general/compositing_manager true

The platform information is :
on giving command uname -a === > Linux 2.6.27-11-generic


Also attached are the testcases.