(Added more info) Cannot drop items from the survival inventory when I changed drop key

What I expected to happen was...:
Cannot drop items from the survival inventory when I changed drop key
"Q" to "\"
I mean this inventory(http://i.imgur.com/KmDX0pH.png)
Not this(http://i.imgur.com/dV2H890.png)
What actually happened was...:
↑Same on
Steps to Reproduce:
1. Go to "Control
2. Change "Drop Selected Item" key "Q" to others. Select "Done"
3. Cannot drop items from the inventory(http://i.imgur.com/KmDX0pH.png)