I loaded up my 0.6.1 world, and tried to take iron out of a furnace, When i clicked the smelted iron to remove it, nothing happened. I tried removing the fuel from the furnace placed in before the update and had the same issue, not being able to remove it. The only thing i could change was where you put the item to be smelted. I ended up having to break the furnace to retrieve the items. You also only select and change the item that is to be smelted. Hope i gave enough information, thanks for your time.