How to handle radio group for NSButton
Use same action, or we can roll our own implementation
An NSButton configured as a radio button (with the -buttonType set to NSRadioButton), will now operate in a radio button group for applications linked on 10.8 and later. To have the button work in a radio group, use the same -action for each NSButton instance, and have the same superview for each button. When these conditions are met, checking one button (by changing the -state to 1), will uncheck all other buttons (by setting their -state to 0).