Cant create slot that accepts any item

GUI slot doesnt allow any item to be put in even though the settings are set so that it can. (Image)

Update 1: By pasting the code snippet below into the code, specifically into the "this.customSlots.put(0, this.addSlot(new SlotItemHandlet(Internal, 0, 25, 8) { }))" section i am able to create a slot that accepts any item. However, it seems that the player MUST shift click it in, as it doesnt allow to player to just place items in normally.
 

@Override
			public boolean mayPlace(ItemStack stack) {
				return true;
			}