As to answer the first question: Yes, rel_for_screen indeed behaved differently in the last beta - this will be corrected. But vec_to_screen is ok - we've looked into it to be sure. For checking an entity visibility, use the return value of vec_to_screen. Your method can only work when the entity is on the screen, but not when it is out of the screen, as then the screen coordinates are not guaranteed to be valid.