I have a frame which contains a button, on clicking on the button a dialog is displayed. I can see that frame & dialog upper corners are not round either they are dark extra pixel is seen like a square. I have attached the screen shot. This works fine in 6u10 b11 promoted build. but fails in 6u10 b12 pit build . Hence its a regression introduced in pit build.

Step to reproduced:-
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1) Run the attached testcase.
2) You can see the frame. Observe that frame's top left & right corner are not round either an extra dark blue square can be seen.
3) Click on the button to display a dialog. Observe that top left & right corner are not round either an extra dark blue square can be seen. If you see the same then the bug is reproduced.