Gtk.Container.prototype.get_focus_chain

function get_focus_chain():Boolean {
    // Gjs wrapper for gtk_container_get_focus_chain()
}

Retrieves the focus chain of the container, if one has been set explicitly. If no focus chain has been explicitly set, GTK+ computes the focus chain based on the positions of the children. In that case, GTK+ stores null in focusable_widgets and returns false.