Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here

What actually happened was...:
Describe what happened here
I was using my furnace, putting in some iron ore but when I tried to put in the fuel like coal or sticks it didn't let me use them.
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ... Build a furnace
3. ...put iron ore in
4. ... Then try to switch to fuel slot