Nimbus L&F : regression : PIT : selection patchs can be seen in scrollpane in pit build

Rendering issues in pit build.

Step to reproduce:
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1) Run Swingset2 .
2) Select Tree demo.
3) open up all the nodes in the tree. so that scrollbar is seen & tumb become very small.
4) select the last node in the tree. Press uparrow key to navigate so that you can travel upward.
5) While navigating observe that a selection ( vertical) line is seen on the left side of the tree. If you see the same then bug is reproduced.

This can be seen only in the respin build. I have attached the screen shot of the same. I tested this on windows vista.