Furnace Bug

I Have A Furnace Bug

*What I expected to happen was....: I Thought That I Would Smelt Iron In The Furnace But It Turns Out I Can't Select The Next Box Or Even Taking Back The Iron Ore....

*What actually happened was...: I Was Mining Around Minecraft PE Then I Found Iron Then I Wanted To Smelt It I Went To The Furnace And The Bug Shows Up

Steps to Reproduce:
1. Take Any Item To Smelt
2. Press Another Box
3. And The Bug Show's Up You Can't Select The Other Box.