void actlist_destroy(actlist_t*a);
int actlist_size(actlist_t*a);
void actlist_verify(actlist_t*a, int32_t y);
-void actlist_dump(actlist_t*a, int32_t y);
+void actlist_dump(actlist_t*a, int32_t y, double gridsize);
segment_t* actlist_find(actlist_t*a, point_t p1, point_t p2); // finds segment immediately to the left of p1 (breaking ties w/ p2)
void actlist_insert(actlist_t*a, point_t p1, point_t p2, segment_t*s);
void actlist_delete(actlist_t*a, segment_t*s);