This project aims to create one storage for all items with Category tabs. For testing, I have to create an Inventory system too. I'm still making improvements.
The inventory system is index-based. Every UMG slot knows its indexes. If a player picks an item, the item is placed into the first empty slot. And, only in that slot is updating the icon and quantity of the item. Drag and drop work the same way—only the drag and drop slots update in the user interface.