{{Infobox version
|title=Minecraft 12w40a
|image=12w40a Banner.png
|image2=Java Edition 12w40a.png
|edition=java
|type=Snapshot
|parent=1.4.2
|date=October 4, 2012
|clientdl=[https://vault.omniarchive.uk/archive/java/client-release/1.4/pre/12w40a.jar Client] ([https://archive.org/download/Minecraft-JSONs/12w40a.json .json])
|serverdl=[https://vault.omniarchive.uk/archive/java/server-release/1.4/pre/12w40a.jar Server]
|exedl=[https://vault.omniarchive.uk/archive/java/server-release/1.4/pre/12w40a.exe .exe]
[[Category:Versions using legacy download site]]
|prevparent=1.3.2
|prev=12w39b
|next=12w40b
|nextparent=1.4.4
}}<onlyinclude>

'''12w40a''' is the tenth [[snapshot]] for [[Java Edition 1.4.2]], released on October 4, 2012.<ref>https://web.archive.org/web/20121006083812/http://www.mojang.com/2012/10/minecraft-snapshot-12w40a/</ref>

== Additions ==
=== World generation ===
; [[Swamp hut]]s
* New generated structure.
* Located in swamp biomes.
* Spawn witches.

=== General ===
; NBT format
* Custom items can now be named using NBT data (intended for custom map makers).
** Using the NBT, it is possible to add custom {{nbt|string|Name}} to [[item]]s, as well as a {{nbt|list|Lore}} list for that item.

; [[Superflat]]
* Added preset "Redstone Ready" with 52 layers of [[sandstone]], 3 layers of [[stone]] and 1 layer of [[bedrock]].

== Changes ==
=== Blocks ===
; [[Beacon]]s
* Texture has been altered.
* Beam texture has also been changed.

; [[Fire]]
* Spreading has been nerfed to prevent infinitely spreading fires.

=== Items ===
; [[Eye of ender]]
* Can now be used in superflat worlds, if the stronghold generation is enabled.

=== Mobs ===
; [[Slime]]s
* Now spawn in [[swamp]] biomes at low light level.

=== Gameplay ===
; [[Inventory]]
* Better management. 
* The pick block action now works on [[block]]s that are represented as [[item]]s in the inventory (e.g.: [[redstone repeater]], [[redstone dust]], and [[tripwire]]).
* Pressing the 1-9 hotkeys while hovering over an item puts that item into the corresponding hotbar slot.
** If there is already an item in the assigned hotbar slot, the hotbar item and the selected item swap position.
** When in [[Creative inventory]], a full stack of that item is transferred to that hotbar slot.
* In Creative mode, players can now shift-click items between the hotbar and the Survival inventory.
* The left-click action no longer opens [[door]]s, pulls [[lever]]s, pushes [[button]]s or opens [[trapdoor]]s.
* When in Creative mode, {{control|pick block}} on an item picks up a stack of that item.

=== General ===
; [[Superflat]]
* Configuration now allows the player to generate [[tree]]s, [[stronghold]]s etc.
* Now [[pumpkin]]s, [[short grass]], [[fern]]s, [[flower]]s, trees, [[mineshaft]]s, [[dungeon]]s, strongholds, [[lake]]s, [[desert well]]s, [[ravine]]s and [[ore]]s spawn on superflat maps.

== Fixes ==
; 13 bugs fixed
* Fixed the wither's starting explosion not being disabled by the <code>mobGriefing</code> gamerule<ref>{{tweet|jeb|252685565147881472}}</ref>
* 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 no longer plays 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.<ref>{{tweet|dinnerbone|252717015553413120}}</ref>
* Fixed being unable to place paintings larger than 1x2 and them popping off if they have been placed before.
* Fixed destroying blocks under the player with efficiency-enchanted gear.
* Fixed potion spawners crashing the game.<ref>{{tweet|dinnerbone|252479682476376065}}</ref></onlyinclude>

== References ==
{{reflist}}

== Navigation ==
{{Navbox Java Edition versions|1.0}}

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