Even though I couldn't find any documentation on new event handlers, playing with them reveals that they are buggy and inconsistent. For example, Dragging backpack to the ground triggers PUT but dragging it back into its slot does not trigger TAKE. Works with clothing and vest though.
Dragging Items from designated slot to inventory or the ground triggers PUT but putting them back into designated slot doesnt trigger TAKE
Putting handgun in inventory from the gun slot doesnt trigger PUT or Take if you drag it back, but it does trigger PUT if you drag it to the ground straight from the slot, and does trigger TAKE for both drag to inventory and directly to the slot.
Action menu Rearm at... doesn't trigger anything even though there is inventory transaction. Action menu Take item ... also can or cannot trigger TAKE depending on what item you take and where it goes as the above explained.
Basically at the moment it is unusable due to inconsistency in behavior.