Called to update the activatable completely, this is called internally when #GtkActivatable:related-action property is set or unset and by the implementor when #GtkActivatable:use-action-appearance changes.
Called to update the activatable when its related action’s properties change. You must check the #GtkActivatable:use-action-appearance property only apply action properties that are meant to effect the appearance accordingly.
> This method can be called with a null action at times.