A toggle button of which only one in a group may be active.
A single radio button performs the same basic function as a
GtkCheckButton, as its position in the object
hierarchy reflects. It is only when multiple radio buttons are grouped
together that they become a different user interface component
in their own right.
Every radio button is a member of some group of radio buttons.
When one is selected, all other radio buttons in the same group
are deselected. A GtkRadioButton is one
way of giving the user a choice from many options.
Radio button widgets are created with
passing null as the argument if this is the first radio
button in a group.
To retrieve the group a GtkRadioButton is assigned to, use
To remove a GtkRadioButton from one group and make it part of a new one,
use set_group() .
Creates a new radio button.
A widget has been added/removed from the group.