Index: trunk/src/layer.c
===================================================================
--- trunk/src/layer.c	(revision 14741)
+++ trunk/src/layer.c	(revision 14742)
@@ -742,6 +742,14 @@
 	return hash;
 }
 
+pcb_layer_type_t pcb_layer_mirror_type(pcb_layer_type_t lyt)
+{
+	if (lyt & PCB_LYT_TOP)
+		return (lyt & ~PCB_LYT_TOP) | PCB_LYT_BOTTOM;
+	else if (lyt & PCB_LYT_BOTTOM)
+		return (lyt & ~PCB_LYT_BOTTOM) | PCB_LYT_TOP;
+	return lyt;
+}
 
 int pcb_layer_type_map(pcb_layer_type_t type, void *ctx, void (*cb)(void *ctx, pcb_layer_type_t bit, const char *name, int class, const char *class_name))
 {
Index: trunk/src/layer.h
===================================================================
--- trunk/src/layer.h	(revision 14741)
+++ trunk/src/layer.h	(revision 14742)
@@ -266,7 +266,10 @@
 /* Calculate a hash of a bound layer (ingoring its name) */
 unsigned int pcb_layer_hash_bound(pcb_layer_t *ly);
 
+/* Calculate mirrored version of some (bound) layer properties */
+pcb_layer_type_t pcb_layer_mirror_type(pcb_layer_type_t lyt);
 
+
 /* Modify tree pointers in dst to point to src's; allocates trees for src if they are not yet allocated */
 void pcb_layer_link_trees(pcb_layer_t *dst, pcb_layer_t *src);
 
Index: trunk/src/obj_subc.c
===================================================================
--- trunk/src/obj_subc.c	(revision 14741)
+++ trunk/src/obj_subc.c	(revision 14742)
@@ -1621,10 +1621,7 @@
 	pcb_subc_mirror(NULL, newsc, yoff, pcb_true);
 	for(n = 0; n < newsc->data->LayerN; n++) {
 		pcb_layer_t *ly = newsc->data->Layer + n;
-		if (ly->meta.bound.type & PCB_LYT_TOP)
-			ly->meta.bound.type = (ly->meta.bound.type & ~PCB_LYT_TOP) | PCB_LYT_BOTTOM;
-		else if (ly->meta.bound.type & PCB_LYT_BOTTOM)
-			ly->meta.bound.type = (ly->meta.bound.type & ~PCB_LYT_BOTTOM) | PCB_LYT_TOP;
+		ly->meta.bound.type = pcb_layer_mirror_type(ly->meta.bound.type);
 	}
 
 	/* place the new subc */