PIT : Canvas is not fully painted on the internal frame & internal frame goes behind the canvas

While doing bug verification for http://monaco.sfbay/detail.jsf?cr=6768332. I observed that when the frame is realised, the first internal which contains the AWT canvas is not painted fully atleast the portion where the red canvas covers the yellow canvas, & the internal frame goes behind the canvas when they are moved on top of another in default lookand feel i,e metal look & feel. This was working properly on 6u12 b01 promoted build & hence its a regression. This issues can be seen in all lookand feel. I have attached the screen shot of the same comparing both 6u12 b01 promoted build & 6u12 b02 pit build

Step to reproduced :-
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1) Run the attached testcase.
2) Move the red internal frame , away from the yellow internal frame. Observe the portion where the red internal frame covers the yellow internal frame is not painted i,e the canvas is not painted . If you see the same then the bug is reproduced.

I tested this in 6u12 b02 pit build on windows xp sp3.