Internal frame buttons(minimize, maximize & close) are not having left vertical line are rendered properly. I have attached screen shots of the problem & correct internal frame screen shot from textpad application.

Step to reproduce:
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1) Run SwingSet2.
2) Select "Internal Frame Demo".
3) Observe that minimize , maximize & close buttons are not rendered properly.

I tested this on jdk1.6.0 & its update releases & jdk1.7.0.