Java Edition 12w40a

12w40a is the tenth snapshot released for 1.4.2.

Additions

 * Added Swamp Hut structures, for Witches to spawn in.
 * Added superflat preset "Redstone Ready" with 52 layers of sandstone, 3 layers of stone, and 1 layer of bedrock.
 * Custom Item naming NBT tags (intended for custom map makers).
 * Using the NBT, it is possible to add custom names to items, as well as a lore list for that item.

Changes

 * Flatworld configuration now allows you to generate trees, strongholds etc.
 * Now pumpkins, tall grass, flowers, trees, mineshafts, dungeons, strongholds, lakes, desert wells, ravines and ores will spawn on superflat maps
 * Better inventory management
 * The pick block action now works on blocks that are represented as items in the inventory. (E.g.: Repeaters, redstone dust, tripwire)
 * Pressing the 1-9 hotkeys while hovering over an item will put that item into the inventory bar.
 * In creative mode, you can now shift-click items from the hotbar to the survival inventory screen
 * The left-click action will no longer open doors, pull levers, push buttons or open trapdoors. Use the right mouse button!
 * Firespread has been slightly nerfed again to prevent infinitely spreading fires
 * Beacon Texture altered, as well as the beam.
 * Eye of Ender can now be used in superflat worlds. (only if stronghold generation is enabled)
 * Slimes now spawn in Swamp biomes at low light level.

Fixes
13 bugs fixed


 * Fixed the wither's starting explosion not being disabled by the mobGriefing gamerule
 * Fixed a few crash bugs related to world generation, map item expansion, and other things.
 * Reverted previous lighting changes, which corrected such bugs as:
 * The Nether being extremely CPU intensive.
 * Map generation taking extremely long.
 * Fixed mob AI considering cobblestone walls as blocks of normal height.
 * Fixed a few texture oddities with the witch.
 * Fixed entities in water producing glitchy water sound.
 * Gaining multiple levels at a time will no longer play the leveling up sound over itself as many times as leveled.
 * Fixed the "A 64 bit Java installation is recommended for 'Far' render distance (you have 32 bit)" message being covered by the bottom 2 buttons.
 * Fixed pets teleporting around randomly
 * Fixed being unable to place paintings larger than 1x2 and them popping off if they have been placed before
 * Fixed destroying blocks under you with Efficiency-enchanted gear
 * Fixed potion spawners crashing the game