+ (SpanBarStub
+ . (
+ (X-extent . ,grob::x-parent-width)
+ (Y-extent . ,(ly:make-unpure-pure-container #f ly:axis-group-interface::pure-height))
+ (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))))))
+