gtk:toggle-button-group (object)

object -- a gtk:toggle-button widget
group -- another gtk:toggle-button widget to form a group with

The accessor for the group slot of the gtk:toggle-button class adds object to the group of group. In a group of multiple toggle buttons, only one button can be active at a time.

Note that the same effect can be achieved via the gtk:actionable API, by using the same action with parameter type and "s" state type for all buttons in the group, and giving each button its own target value.