Index: trunk/src/obj_subc.c
===================================================================
--- trunk/src/obj_subc.c	(revision 16986)
+++ trunk/src/obj_subc.c	(revision 16987)
@@ -1714,3 +1714,15 @@
 	sc->data->Layer[n].type = PCB_OBJ_LAYER;
 	return &sc->data->Layer[n];
 }
+
+void pcb_subc_part_changed_(pcb_any_obj_t *obj)
+{
+	pcb_subc_t *sc = pcb_obj_parent_subc(obj);
+	if (sc == NULL)
+		return;
+
+	/* can't do this incrementally: if a boundary object is smaller than before
+	   it has to make the subc bbox smaller too */
+	pcb_subc_bbox(sc);
+}
+
Index: trunk/src/obj_subc.h
===================================================================
--- trunk/src/obj_subc.h	(revision 16986)
+++ trunk/src/obj_subc.h	(revision 16987)
@@ -125,6 +125,10 @@
 /* Returns whether there's no object in the subc */
 pcb_bool pcb_subc_is_empty(pcb_subc_t *subc);
 
+/* Update the subcircuit (e.g. bbox) after a part of the subcircuit has changed */
+void pcb_subc_part_changed_(pcb_any_obj_t *obj);
+#define pcb_subc_part_changed(obj) pcb_subc_part_changed_((pcb_any_obj_t *)obj)
+
 /*** subc creation helpers ***/
 
 /* Create the aux layer for a subc, set origin to ox;oy and rotation to rot */