I can't click on the icons inside the furnace!

Put the summary of the bug you're having here

What I expected to happen was: craft a furnace and cook my porkchops
Describe what you thought should happen here

What actually happened was: I clicked on the icon in the furnace to place in my coal and it wouldn't select the icon
Describe what happened here

Steps to Reproduce:
1. Create a furnace
2. Click on it
3. Click on bottom icon