(Sorry for my bad English)
I was testing a redstone circuit, and I need to have a brewing stand with 64 items in the ingredients'slot, and next have 63, so I put 64 redstone in the brewing stand and 63 in my inventory. Then, I made double left-click in the slot with 63 redstone.
What I expected to happen was...:
I expected to have 64 redstone in my inventory and it be 63 in the brewing stand.

What actually happened was...:
I had 64 redstone in my inventory, but there wasn´t anything in the brewing stand!

Steps to Reproduce:
1. Place a brewing stand with some items in one of its slots.
2. Put some of the same item in your inventory. You MUSN'T have more then 63 in your inventory, and you MUST have more than 64 in your inventory with the brewing stand.
3. Do double left-click with your mouse in the stack in your inventory.

Extra thinks:
-It only works in brewing stands (well, I dind't check that in all the bloks with inventory, but I did it with the most)
-It works in any slot of the stand. I have tested that with a bug in the brewing stands and the bottles.