Steps to reproduce:

1. Run SwingSet2 on Windows Vista (It's also reproducible on XP with
 -Dsun.java2d.noddraw=true supplied)
2. Open "Look&Feel" menu and select "Windows Style Look&Feel" item
3. Open "Look&Feel" menu once again. You'll see non-round selected RadioButton

The problem is that on Vista some rendering operations including filling of the complex
 shapes go through software pipeline. This pipeline was changed in jdk6 to have fill
 operation aligned with draw. Unfortunately, it caused some rendering problems in
 applications depended on old fill behavior. Such problems could be easily resolved
 just by setting following rendering hint before the fill code:

g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,
                   RenderingHints.VALUE_STROKE_PURE);