There is no shield/second hand slot in the crafting table interface.

I was making a furnace and expected to be able to use the cobblestone I store in my shield slot. To my dismay, this slot isn't accessible from the crafting table GUI!

What I expected to happen was...:
Use my 8 cobblestone in my shield slot to make a furnace

What actually happened was...:
I had to exit the GUI and open my inventory to get the cobble out, then go back into the GUI to craft it.

Steps to Reproduce:
1. Put items in your shield slot
2. Open a crafting table
3. Craft something with said items