Books with photos that move - Harry Potter-style - may soon be with us. But before that, get ready for boxes of cereal that extol their own virtues via a built-in video display and chocolate bars that flash and flare to attract your attention. Siemens has announced a new type of colour display screen so thin and flexible it can be printed onto paper or foil, and so cheap it can be used on throwaway packaging. A spokesman for the company, Dr Norbert Aschenbrenner, said the screens would be able to do everything a conventional TV could, albeit with slightly lower quality. The first examples would be on the market by 2007, Dr Aschenbrenner said.