This is called to update the activatable completely, this is called internally when the "related-action" property is set or unset and by the implementing class when "use-action-appearance" changes. Since 2.16
the related GtkAction or NULL. [allow-none]
See Implementation
This is called to update the activatable completely, this is called internally when the "related-action" property is set or unset and by the implementing class when "use-action-appearance" changes. Since 2.16