$NetBSD: patch-ad,v 1.1 2006/03/03 04:46:50 minskim Exp $

--- agent.h.orig	2001-06-15 18:53:10.000000000 -0700
+++ agent.h
@@ -70,7 +70,7 @@ public:
   inline double width()  {return width_;}
   inline double height() {return height_;}
   virtual void findClosestCornertoPoint(double x, double y, 
-               double &corner_x, double &corner_y) const = NULL; 
+               double &corner_x, double &corner_y) const = 0; 
   virtual void place(double x, double y);
   void label(const char* name, int anchor);
   void color(const char* name);