The default look and feel for Java6u10 has become SystemLookAndFeel (com.sun.java.swing.plaf.windows.WindowsLookAndFeel in case of Windows) instead of CrossPlatformLookAndFeel (javax.swing.plaf.metal.MetalLookAndFeel).
Load the attached JAppet into any browser. Look at the console to know which look and feel it is using. If it is not MetalLookAndFeel, this bug is reproducible.
The same issue is applicable with plugin2 also.
This is a regression, Java1.6.0 loads the same applet with into the browser using Java look (javax.swing.plaf.metal.MetalLookAndFeel) and feel which is the correct behavior.
Note : The attached JApplet uses Java look and feel when viewed using AppletViewer, but uses Windows look and feel when tried with browser (using Java6u10).
Also look at the attached screenshot.