BetterOffhand

Have you ever placed a torch with your offhand while you were actually trying to place a block with your main hand? Do you think your offhand could be smarter? This is what BetterOffhand has to offer.

When the items held in both your hands are right-clickable on blocks, your offhand will be disabled. Items right-clickable on blocks include: blocks, torches, stairs, slabs, redstone, doors, flint & steel, shovels, hoes, minecarts, leads and seeds.

Changelog:

• 0.2 Using offhand items on blocks will be disabled when holding a consumable item (food or potion) in main hand.

Plans for next release:

• making it purely client-sided - right now it has to be installed in server too.
• disabling the offhand even if you run out of an item until you release the right click.
• configuration options.

Supported MC versions: 1.12.2.

This bug has been partially fixed in vanilla starting from version 1.13.