> This list of characters that will be double-width is known. While that is true, don't they sometimes add new characters into Unicode? (And you might want characters which aren't in Unicode. To represent them as Unicode, you would need to use private codepoints, and unless ranges are defined as narrow/wide, this won't work so well.) Also, some characters have an ambiguous width, and they have occasionally changed some. (My own solution is to not use Unicode, but some people will use Unicode anyways.)