Can not shift and left click in the horses, mule and donkey inventory!

What I expected to happen was...:
When I killed a squid, it should have dropped an ink sac.

What actually happened was...:
Instead, it dropped an apple.

Steps to Reproduce:
1. Get a random item.
2. Get a horse,mule or donkey
3. Open horse,mule or donkey inventory.
4.Hold shift and left click on the item!