Don't destroy files when encountering characters that can't be encoded

Today when Sublime saves a file and encounters a character that can't be encoded in eg ISO-8859-1, it automatically converts it to UTF-8 (and informs you with a popup dialog with just one option - OK). This destroys the file (UTF-8 encoding is in many cases non reversible), so it would be nice if this instead was a question. It would also be very nice if Sublime could highlight or somehow search for unencodable characters (characters like non-braking space is _very_ difficult to distinguish from a normal space).