Index: trunk/src/draw.h
===================================================================
--- trunk/src/draw.h	(revision 8432)
+++ trunk/src/draw.h	(revision 8433)
@@ -101,5 +101,7 @@
 	pcb_layer_t *layer;
 } pcb_draw_info_t;
 
+/* Returns whether lay_id is part of a group that is composed of multiple layers */
+int pcb_draw_layer_is_comp(pcb_layer_id_t lay_id);
 
 #endif
Index: trunk/src/draw_composite.c
===================================================================
--- trunk/src/draw_composite.c	(revision 8432)
+++ trunk/src/draw_composite.c	(revision 8433)
@@ -151,3 +151,10 @@
 	if (!adding)
 		comp_start_add(ctx);
 }
+
+int pcb_draw_layer_is_comp(pcb_layer_id_t id)
+{
+	pcb_layer_group_t *g = pcb_get_layergrp(PCB, PCB->Data->Layer[id].grp);
+	if (g == NULL) return 0;
+	return (g->len > 1);
+}