China's Xi draws 'red line' in Hong Kong as protesters march

China's President Xi Jinping warned on Saturday that any challenge to Beijing's control over Hong Kong crossed a "red line", as thousands calling for more democracy marched through the city 20 years since it was handed back by Britain.Xi spoke in a televised address after swearing in new Hong Kong leader Carrie Lam, who is already being cast by critics as a China stooge in a city where many are angry at Beijing's tightening grip on the freedoms of its nearly eight million people.A huge security