+ (SpanBarStub
+ . (
+ (X-extent . ,grob::x-parent-width)
+ (extra-spacing-height . ,pure-from-neighbor-interface::extra-spacing-height)
+ (Y-extent . #f)
+ (meta . ((class . Item)
+ (object-callbacks . ((pure-Y-common . ,ly:axis-group-interface::calc-pure-y-common)
+ (pure-relevant-grobs . ,ly:pure-from-neighbor-interface::calc-pure-relevant-grobs)))
+ (interfaces . (pure-from-neighbor-interface))))))
+