MinecraftForge/MinecraftForge — pull request #340 by ScottKillen (2012-12-26 16:39:44+00:00)
Title: Add ability to WorldTypes to display the 'Customize' button and react to it.

Very small change to allow a custom WorldType to activate the "Customize" button and provide a hook to display its own gui in reponse to the button push.