SHANGHAI (REUTERS).- Shanghai officially opened its multi-billion-dollar Expo Friday with a dazzling display of fireworks, lasers and dancing fountains, amid tight security and the virtual shutdown of its main Pudong financial district. After a rather low-key performance by singers and dancers in an indoor arena, the ceremony moved outside, with fireworks exploding off bridges and fountains shooting water up as high as 80 meters (263 ft). Some 6,000 LED fuchsia, red and yellow balls floated into the murky Huangpu River, creating a bright sea of balloons against the black water. “The World Expo is a grand event to showcase the best achievements of human civilization. It is also a great occasion for people from around the world to share joy and friendship,” President Hu Jintao told a welcome dinner for foreign leaders. “As the first registered World Expo hosted by a developing country, the Shanghai Expo will be an opportunity for China and also for the world,” Hu added, to an audi