I set up a dialog with 2 radio buttons, and use a boolean to check them programmatically.
// Not working day radio button
final Button notWorkingDayButton = new Button(mSelectedDayGroup, SWT.RADIO);
notWorkingDayButton.setSelection(isWorkingDay);
notWorkingDayButton.setText("Jour chômé"+(isHoliday ? deft : ""));
// Working day radio button
final Button workingDayButton = new Button(mSelectedDayGroup, SWT.RADIO);
workingDayButton.setText("Jour travaillé"+(isHoliday ? "" : deft));
workingDayButton.setSelection(!isWorkingDay);
As you can see, they use the same boolean so they always have opposed states.
Here’s how it looks like if isWorkingDay is true: 
Here’s how it looks like if isWorkingDay is false: 
As you can see the first radio stays somewhat enabled. I want the first one to be completely disabled and the second one completely enabled when isWorkingDay = false.
I don’t have a Mac but this looks like the keyboard focus to me. There is no “somewhat enabled” state for radio buttons.