InventoryTransactionEvent

Did anyone knows how to get the slot (int) From the item in the chest that i want to transfer?

yes...example:

PHP:

        foreach ($ev->getTransaction()->getTransactions() as $baseTransaction) {
            if ($baseTransaction->getInventory() instanceof \pocketmine\inventory\PlayerInventory) {
                $plInvSlot = $baseTransaction->getSlot();
                $plFromItem = clone $baseTransaction->getSourceItem();
                $plToItem = clone $baseTransaction->getTargetItem();
            } elseif ($baseTransaction->getInventory() instanceof \pocketmine\inventory\ChestInventory) {
                $chInvSlot = $baseTransaction->getSlot();
                $chFromItem = clone $baseTransaction->getSourceItem();
                $chToItem = clone $baseTransaction->getTargetItem();
            } else {
                break;
            }
        }

and if you know how google works , you can try it , i'm saying that for you because google is more fast than us and maybe you can find the answer fastly... i found some examples here: https://github.com/Muirfield/pocket...er/GrabBag/src/aliuly/common/ShoppingCart.php

THX but i search already but nothing was found xD what is $event->getTransaction() ? In the event class there a very empty xD

is a pocketmine/inventory/SimpleTransactionGroup