Shift Click - Deletes Items

When shift clicking inventory items in your 'backpack', and they have nowhere to go (ie, to a chest/furnace inventory, or in the case that particular armor slot is occupied), instead of doing nothing, the item just vanishes - very similar to the creative mode delete box.

Shift clicking when in the "E" inventory screen just flat out deletes them.
Same issue replicated on a horse.

unconfirmed: mule with inventory