for (set<Grob *>::const_iterator it (colliding_stems.begin ()); it != colliding_stems.end (); it++)
{
Grob *s = *it;
- Real x = (s->extent (common[X_AXIS], X_AXIS) - x_pos[LEFT] + x_span_).center ();
+ Real x = (robust_relative_extent (s, common[X_AXIS], X_AXIS) - x_pos[LEFT] + x_span_).center ();
Direction stem_dir = get_grob_direction (*it);
Interval y;