Why, oh why, for selecting either a stack of metal or the smelter to smelt metal are you given the option of Just One, when the minimum is Five? I assume it's an artifact from the standard [ALL|JUSTONE|X] layout, but could that Just One be changed to something that presents actual use as far as smelting is concerned?
Furthermore, why not make a stack four or less of metal have the Smelt verb greyed out, as to indicate that they cannot be used? Just some aesthetic suggestions.