+/* Sets Rect r to be the intersection of Rect a and b. */
+#define RECT_SET_INTERSECTION(r, a, b) \
+ ((r).x = MAX((a).x, (b).x), \
+ (r).y = MAX((a).y, (b).y), \
+ (r).width = MIN((a).x + (a).width - 1, \
+ (b).x + (b).width - 1) - (r).x + 1, \
+ (r).height = MIN((a).y + (a).height - 1, \
+ (b).y + (b).height - 1) - (r).y + 1)
+
+/* Returns the shortest manhatten distance between two rects, or 0 if they
+ intersect. */
+static inline gint rect_manhatten_distance(Rect r, Rect o)
+{
+ if (RECT_INTERSECTS_RECT(r, o))
+ return 0;
+
+ gint min_distance = G_MAXINT;
+ if (RECT_RIGHT(o) < RECT_LEFT(r))
+ min_distance = MIN(min_distance, RECT_LEFT(r) - RECT_RIGHT(o));
+ if (RECT_LEFT(o) > RECT_RIGHT(r))
+ min_distance = MIN(min_distance, RECT_LEFT(o) - RECT_RIGHT(r));
+ if (RECT_BOTTOM(o) < RECT_TOP(r))
+ min_distance = MIN(min_distance, RECT_TOP(r) - RECT_BOTTOM(o));
+ if (RECT_TOP(o) > RECT_BOTTOM(r))
+ min_distance = MIN(min_distance, RECT_TOP(o) - RECT_BOTTOM(r));
+ return min_distance;
+}
+
+typedef struct _Strut {