This is a brute force prevention measure for numerous dupe exploits via disabling Quick-Swapping in inventories.
This includes moving items back and forth from the hotbar using the 1-9 keys, and sending items to and from the offhand slot by pressing F inside an inventory.
This mod prevents Dupe Exploits involving unhandled Quick-Swapping in portable item containers[eg backpacks] in a number of mods including but not limited to:
Immersive Engineering
Applied Energistics 2
Engineer's Tools [fixed as of 1.1.7]
Corail Backpack
Tetra
Blood Magic
Botania
This mod is to act as a stopgap measure for servers until these mods patch their respective issues- all of which I have already reported