A diplomatic feud between Beijing and Tokyo appears to have spilled over to the arts, with what looks like an unofficial boycott on Japanese film, music and books. China has slapped official restrictions on tourism and trade with Japan since the row erupted in November, but so far there has been no official ban on the cultural sector. However, the Shanghai International Film Festival, which begins this Friday, does not have any Japanese films on its line-up for the first time in 20 years. It...