When you try to put things in or get stuff out of the furnace, it won't let you.

I expected to get the iron out of my furnace I put in.

But, what happened was I ended up having to destroy the furnace to get my iron but I couldn't put my coal back in.

Steps to Reproduce:
1. If you click on the furnace and try to pick either where you put the thing that burns at, it won't let you select it.
2.Then if you try to select the box where the product would be at at won't let you either.