Ever had this?? You want to sell one item (e.g. MFSU) but you also have only one so you can´t trade it. Because of that i would be pleased if it would be possible to put the one you have in the locked sell slot and if anyone wants to buy it he pays and then the one on the locked slot should be moved to the unlocked so that he can take it.
I would also like if there would be two out and input slots( e.g. you could sell a lava cell for a empty cell and 2 coins or flint for money and gravel).