A neat improvement could be the possibility to avoid picked up items to go into certain rows or slots.
For instance while mining I don't want to full all my slots with cobblestone, I could then set that A 1-3 can't be filled with picked from ground items, hence these slots can be occupied only when I manually move an item in them.

Alongside with this when shift-clicking from a chest the items always go into the first free slot, is there a way to set that my inventory must be filled from row C upwards?

Thanks in advance.

Due to how the on-pickup thing works I don't think I can keep a slot entirely free. Even if it auto-sorted out of that slot in the event an item ended up there, nothing can really be done if it is the last open slot, as the pure-client mode can't stop an item from being picked up.

Shift-click is also a vanilla function, so the same sort of limitations apply -- a sort/move could probably be scheduled afterwards, but I can't directly interfere with where the item goes initally.

Well if is the case of the last slot available I can understand the difficulty in change the behavior, for the case instead were there is room a new rule in the config file that keeps a slot clean would be difficult to implement?

What about having the player immediately drop the item if it's not wanted when it's picked up