Labels

Anvils sometimes destroy items when falling on them even if they aren't placed successfully

Stacking Splash potions

Stacking anvil graphical glitch

Server consoles will usually output SocketExceptions.

You can't half your items when right clicking things out of a brewing stand.

Right click on crafting table

The give command will stack any item

Item Frames can be stacked on a wall

Cakes are stackable in MCX360 but not the PC version

Enchanted Item Bug in 3D

Another kind? of hopper duplication glitch (stack duplication)

Slabs Have Messy Drop Alignment

Powered hoppers won't accept items

Double clicking in creative inventory doesn't auto stack the items.

Minecarts don't stack, instead moving into the same block.

Hopper Won't Fill Incomplete Stacks

Clicking hotbar hotkey (1-9) to move a stack of items / blocks to enchanting table deletes all but one of a stack

Right-clicking outside of the inventory tab while holding a stack drops whole stack

bad text size for item stacks on iPad 3

Efficiency Enchantment book with pickaxe not stacking

Unstackable Buckets

Can't break blocks in creative with 64 swords

Items do not stack on the correct stack

Whole stack drop by just pressing q

items given using the dataTag do not stack after logging back in

Ctrl+Q to drop a stack of items no longer works

potion graphic bug

Stack Size number displays behind on enchanted items.

Not really a bug...

Duplicated items