SpoutDev/Spoutcraft — comment on commit 0808e8aa7d7d4fb620fc402f9bdcdab80dcc0fde
File: src/minecraft/org/spoutcraft/client/gui/singleplayer/GuiCreateWorld.java line 245
By Top-Cat:

I know tips can't see it, but http://forums.spout.org/threads/1173/