Index: trunk/src/obj_arc.c
===================================================================
--- trunk/src/obj_arc.c	(revision 20159)
+++ trunk/src/obj_arc.c	(revision 20160)
@@ -56,6 +56,24 @@
 static int pcb_arc_end_addr = 1;
 int *pcb_arc_start_ptr = NULL, *pcb_arc_end_ptr = &pcb_arc_end_addr;
 
+void pcb_arc_reg(pcb_layer_t *layer, pcb_arc_t *arc)
+{
+	arclist_append(&layer->Arc, arc);
+	assert(layer->parent_type == PCB_PARENT_DATA);
+	pcb_obj_id_reg(layer->parent.data, arc);
+	PCB_SET_PARENT(arc, layer, layer);
+}
+
+void pcb_arc_unreg(pcb_arc_t *arc)
+{
+	pcb_layer_t *layer = arc->parent.layer;
+	assert(arc->parent_type == PCB_PARENT_LAYER);
+	arclist_remove(arc);
+	assert(layer->parent_type == PCB_PARENT_DATA);
+	pcb_obj_id_del(layer->parent.data, arc);
+	PCB_SET_PARENT(arc, layer, NULL);
+}
+
 pcb_arc_t *pcb_arc_alloc(pcb_layer_t * layer)
 {
 	pcb_arc_t *new_obj;
@@ -63,9 +81,9 @@
 	new_obj = calloc(sizeof(pcb_arc_t), 1);
 	new_obj->type = PCB_OBJ_ARC;
 	new_obj->Attributes.post_change = pcb_obj_attrib_post_change;
-	PCB_SET_PARENT(new_obj, layer, layer);
-	arclist_append(&layer->Arc, new_obj);
 
+	pcb_arc_reg(layer, new_obj);
+
 	return new_obj;
 }
 
@@ -266,10 +284,10 @@
 
 
 
-void pcb_arc_free(pcb_arc_t * data)
+void pcb_arc_free(pcb_arc_t *arc)
 {
-	arclist_remove(data);
-	free(data);
+	pcb_arc_unreg(arc);
+	free(arc);
 }
 
 
@@ -377,8 +395,8 @@
 	pcb_poly_restore_to_poly(ctx->buffer.src, PCB_OBJ_ARC, srcly, arc);
 	pcb_r_delete_entry(srcly->arc_tree, (pcb_box_t *) arc);
 
-	arclist_remove(arc);
-	arclist_append(&dstly->Arc, arc);
+	pcb_arc_unreg(arc);
+	pcb_arc_reg(dstly, arc);
 
 	PCB_FLAG_CLEAR(PCB_FLAG_FOUND, arc);
 
@@ -387,8 +405,6 @@
 	pcb_r_insert_entry(dstly->arc_tree, (pcb_box_t *) arc);
 	pcb_poly_clear_from_poly(ctx->buffer.dst, PCB_OBJ_ARC, dstly, arc);
 
-	PCB_SET_PARENT(arc, layer, dstly);
-
 	return arc;
 }
 
@@ -613,15 +629,13 @@
 {
 	pcb_r_delete_entry(Source->arc_tree, (pcb_box_t *) arc);
 
-	arclist_remove(arc);
-	arclist_append(&Destination->Arc, arc);
+	pcb_arc_unreg(arc);
+	pcb_arc_reg(Destination, arc);
 
 	if (!Destination->arc_tree)
 		Destination->arc_tree = pcb_r_create_tree();
 	pcb_r_insert_entry(Destination->arc_tree, (pcb_box_t *) arc);
 
-	PCB_SET_PARENT(arc, layer, Destination);
-
 	return arc;
 }
 
Index: trunk/src/obj_arc.h
===================================================================
--- trunk/src/obj_arc.h	(revision 20159)
+++ trunk/src/obj_arc.h	(revision 20160)
@@ -52,6 +52,9 @@
 pcb_arc_t *pcb_arc_dup_at(pcb_layer_t *dst, pcb_arc_t *src, pcb_coord_t dx, pcb_coord_t dy);
 void *pcb_arc_destroy(pcb_layer_t *Layer, pcb_arc_t *Arc);
 
+void pcb_arc_reg(pcb_layer_t *layer, pcb_arc_t *arc);
+void pcb_arc_unreg(pcb_arc_t *arc);
+
 /* Add objects without creating them or making any "sanity modifications" to them */
 void pcb_add_arc_on_layer(pcb_layer_t *Layer, pcb_arc_t *Arc);
 
Index: trunk/src/obj_common.h
===================================================================
--- trunk/src/obj_common.h	(revision 20159)
+++ trunk/src/obj_common.h	(revision 20160)
@@ -216,6 +216,15 @@
 /* Returns the first invalid character of an ID (terminal, refdes) or NULL */
 const char *pcb_obj_id_invalid(const char *id);
 
+#define pcb_obj_id_reg(data, obj) \
+	do { \
+		pcb_any_obj_t *__obj__ = (pcb_any_obj_t *)(obj); \
+		htip_set(&(data)->id2obj, __obj__->ID, __obj__); \
+	} while(0)
+
+#define pcb_obj_id_del(data, obj) \
+	htip_pop(&(data)->id2obj, (obj)->ID)
+
 #define pcb_hidden_floater(obj) (conf_core.editor.hide_names && PCB_FLAG_TEST(PCB_FLAG_FLOATER, (obj)))
 
 /* Returns whether a subc part object is editable (not under the subc lock) */
Index: trunk/src/obj_subc.c
===================================================================
--- trunk/src/obj_subc.c	(revision 20159)
+++ trunk/src/obj_subc.c	(revision 20160)
@@ -483,9 +483,8 @@
 		}
 
 		while((arc = arclist_first(&src->Arc)) != NULL) {
-			arclist_remove(arc);
-			arclist_append(&dst->Arc, arc);
-			PCB_SET_PARENT(arc, layer, dst);
+			pcb_arc_unreg(arc);
+			pcb_arc_reg(dst, arc);
 			PCB_FLAG_CLEAR(PCB_FLAG_WARN | PCB_FLAG_FOUND | PCB_FLAG_SELECTED, arc);
 		}