Mojang should prevent the world from generating if the top block is non opaque.
2012-11-25, 10:12:15 PM UTC
Java 7u9, Windows 7 64 bit, Intel Core i5, 2 real cores, 2 "fake" cores (each core acts as 2), 6 gb of ram
Mojang should prevent the world from generating if the top block is non opaque.