Making inventory items fill up empty spaces

[RansomHostage]

Hello,

I am using the tutorial for the simple inventory system located here.

I've got it working fine within my game I'm making. However, if the player uses an item in the middle (or, in fact, anywhere other than the end) of the inventory list, it leaves a gap where it once was. How would I go about making each of the found items in the inventory move back one slot upon the player using an item?

I've uploaded a sample of my current inventory system here. To understand what I mean, pick up all four items (in any order) and then "use" one of the first three items you picked up. You should see a gap has been left in the inventory. I want this gap to be filled in by the remaining items in the inventory once said item has been used.

I've been thinking about it and I think a method that may work would be to do a hit test for all of the slots every time an item is used (to check if any slots don't have any items overlapping them), and move all of the items that are positioned to the right of it left by 60 pixels (as each slot and item is 60x60). This could work in theory but I'm not sure if it's the best method, or how to actually do it.

Does anyone know how I could achieve this? Or know of any better tutorials for inventory systems that include this feature already?

Thank you in advance.

[RansomHostage]

Any ideas?