! for themed maps you wouldn't really need two columns like Jeremy said. It would be enough to have a button in the city editor, that makes appear the screen for buying units like the one in-game, and instead of 'buy' you could choose to 'disallow' or 'allow' again production of a certain unit. That would be simpler I think . Then the button in the city editor could be grayed out (not selectable) in read-only mode, so players couldn't see what they can buy in a city, and you wouldn't have advantages by checking the map in the editor.