Java Edition 12w15a

12w15a is the first snapshot released for 1.3.1.

Blocks

 * Dispensers
 * Dispensers will deploy boats on water, and minecarts on rails, powered minecarts and storage minecarts are also deployed similar to mine carts.

Items

 * General
 * Stackable items now stack outside inventory when thrown to the ground individually.

Mobs

 * Slimes
 * Decreased slime spawning rate in superflat worlds.

Non-mob entities

 * Minecart with furnace
 * Right-clicking a powered minecart in creative will act as if you would give it coal.

General

 * Controls
 * “Pick Block" button now gives the correct block when used; when clicking on a mob, it gives the appropriate spawn egg.
 * +clicking can now be used to wear armor.
 * +clicking can now be used to put items in brewing stands and enchantment tables.