In Episode 04 of my Ultra Modular Inventory + Interaction System series for Unreal Engine 5.4, I focus on cleaning up a nasty drag-and-drop edge case: if you dragged an item onto a slot that was already at max stack size, the UI would wig out and you could end up deleting items. I fix this inside my Item Container Component by adding a simple max-stack check (using a new Blueprint Function Library helper) so that when the target stack is already full, the drag just cancels instead of doing anything destructive. I also add a “Stackable?” boolean to my primary item data asset. The idea is simple: later on, stuff like swords/equipment shouldn’t stack even if you technically could force it by setting max stack to 1. With the new “Is Item Stackable?” function, I gate the “already exists in inventory” add-path so non-stackable items don’t merge into a stack. To finish it off, I add some UI juice: a subtle hover scale animation on the item widget (with nicer curves in the graph editor), tweak playback speed, and hook up randomized hover sounds using a Sound Cue with a Random node and Modulators for pitch/volume variation. I also add quick open/close inventory sounds to give the whole UI more character.