Top right box in inventory is glitchy

Put the summary of the bug you're having here

What I expected to happen was...:
I was trying to place items in the top right corner box in my inventory, and I could not get the items to go in the box.

What actually happened was...:
The items would not go into the box and my mouse would freeze for a few seconds. If I tried a few more times though, the items eventually went into the box. It was even harder to drag items out of that box. I to either wait a minute or empty a box in my hot bar and drop the item in that corner box to use it (hit q on the box). Also, my mouse sometimes froze if it went near that box.

Steps to Reproduce:
1. Have item in inventory
2. Try to move it the the top right corner box in my inventory (it doesn't go in)
3. Try several more times and it eventually goes in

OR

1. Have item in top right corner box of inventory
2. Try to drag it out of box and it doesn't move
3. Wait a minute and then try it and it works