Index: ChangeLog
===================================================================
RCS file: /cvs/cairo/cairo/ChangeLog,v
retrieving revision 1.1076
diff -u -r1.1076 ChangeLog
--- ChangeLog	29 Sep 2005 21:31:08 -0000	1.1076
+++ ChangeLog	30 Sep 2005 00:14:59 -0000
@@ -1,3 +1,10 @@
+2005-09-30  Bertram Felgenhauer  <int-e@gmx.de>
+
+	* src/cairo-hull.c (_cairo_hull_create),
+	(_cairo_hull_vertex_compare): Using a pointer comparison as the
+	fallback total order was wrong - these pointers are not stable.
+	So we introduce our own total order instead. 
+
 2005-09-29  Keith Packard  <keithp@keithp.com>
 
 	reviewed by: cworth
Index: src/cairo-hull.c
===================================================================
RCS file: /cvs/cairo/cairo/src/cairo-hull.c,v
retrieving revision 1.9
diff -u -r1.9 cairo-hull.c
--- src/cairo-hull.c	21 Aug 2005 18:41:44 -0000	1.9
+++ src/cairo-hull.c	30 Sep 2005 00:14:59 -0000
@@ -41,6 +41,7 @@
     cairo_point_t point;
     cairo_slope_t slope;
     int discard;
+    int id;
 } cairo_hull_t;
 
 static cairo_hull_t *
@@ -70,10 +71,13 @@
 	_cairo_slope_init (&hull[i].slope, &hull[0].point, &hull[i].point);
 
 	/* Discard all points coincident with the extremal point */
-	if (i != 0 && hull[i].slope.dx == 0 && hull[i].slope.dy == 0)
+	if (i != 0 && hull[i].slope.dx == 0 && hull[i].slope.dy == 0) {
 	    hull[i].discard = 1;
-	else
+            hull[i].id = -i;
+        } else {
 	    hull[i].discard = 0;
+            hull[i].id = i;
+        }
     }
 
     return hull;
@@ -98,11 +102,11 @@
 	b_dist = ((cairo_fixed_48_16_t) b->slope.dx * b->slope.dx +
 		  (cairo_fixed_48_16_t) b->slope.dy * b->slope.dy);
 	/*
-	 * Use pointer comparison for coincident points to ensure
+	 * Use the point's ids to ensure a total ordering.
 	 * a well-defined ordering, and avoid setting discard on
-	 * both points.
+	 * both points.          
 	 */
-	if (a_dist < b_dist || (a_dist == b_dist && a < b)) {
+	if (a_dist < b_dist || (a_dist == b_dist && a->id < b->id)) {
 	    a->discard = 1;
 	    ret = -1;
 	} else {