--- a/src/frame.h	Fri Mar 05 04:08:17 2010 -0600
+++ b/src/frame.h	Sun Mar 07 02:09:59 2010 -0600
@@ -161,4 +161,18 @@
 
 void init_frame (void);
 
+enum edge_pos
+{
+  TOP_EDGE,
+  BOTTOM_EDGE,
+  LEFT_EDGE,
+  RIGHT_EDGE,
+  NUM_EDGES
+};
+
+/* Iterate over all possible edge positions */
+#define EDGE_POS_LOOP(var)				\
+  for (var = (enum edge_pos) 0; var < NUM_EDGES;	\
+       var = (enum edge_pos) (var + 1))
+
 #endif /* INCLUDED_frame_h_ */