balloon-text: robust with empty stencils; issue 4447

diff --git a/lily/balloon.cc b/lily/balloon.cc
index 2b898c3d25958d4a5c30c1748ca55c13c8278289..7e8067a577ac5db20ceb8129e977a2edf27ee819 100644 (file)
--- a/lily/balloon.cc
+++ b/lily/balloon.cc
@@ -88,8 +88,8 @@ Balloon_interface::print_spanner (SCM smob)
 SCM
 Balloon_interface::internal_balloon_print (Grob *me, Grob *p, Offset off)
 {
-  Box b (p->extent (p, X_AXIS),
-         p->extent (p, Y_AXIS));
+  Box b (robust_relative_extent (p, p, X_AXIS),
+         robust_relative_extent (p, p, Y_AXIS));
   Real padding = robust_scm2double (me->get_property ("padding"), .1);
   b.widen (padding, padding);