Easily create your own collections, simply drag on a component, play with the settings in the inspector and voila. The skillbar uses references, and sums up the total amount of items in the inventories.
Filter collections (any window with items in it). For example when you create multiple inventories (which is very possible) you can filter one to only allow quest items.
Restrict your collections to types, weight, dragging, (un)stacking and more. This allows you to create a collection that can only hold consumable items, only quest items or both.
Categories can be given a cooldown, all items sharing this category will all go into cooldown when an item from this category is used. Of course you can override the cooldown per item.
Allow each item to take up a specified amount of space in your collections. For example, allow a shield to take up a 2x2 slot while an apple only takes a 1x1 slot.
Sort, re-stack and tidy up your collections with a simlpe click of a button. The sorting algorithm can be tweaked to your liking to sort based on any paramter or type.