In windows L&F(Using OS Windows 2000) Selected color mark of JCheckBox and
JRadioButton are not same as native.
These both components are using selected mark color as RGB 66, 65, 66 i.e color
dark gray, while in native selected mark color is black i.e. RGB 0, 0, 0

Consider attached image: CheckRadioCmp.PNG
It clearly shows this difference.