Sets the related action on the activatable object.
> #GtkActivatable implementors need to handle the #GtkActivatable:related-action > property and call gtk.activatable.Activatable.doSetRelatedAction when it changes.
the #GtkAction to set
Sets the related action on the activatable object.
> #GtkActivatable implementors need to handle the #GtkActivatable:related-action > property and call gtk.activatable.Activatable.doSetRelatedAction when it changes.