Rows of body bags were laid out along streets for all to see. Sobbing parents furious about shoddily built schools that collapsed and killed thousands of children were able to speak freely. Military helicopters carried reporters to tour the disaster zone.  The earthquake that flattened a wide swath of central Sichuan province May 12 has been a historic event for journalism in China. Never before have the nation's leaders allowed foreign reporters so much freedom to cover a major disaster. Chinese leaders haven't fully explained the new openness, and periods of thaw can be brief here. Only time will tell if it is a real policy shift a bold break from the Communist Party's traditional tight control on the release of news, particularly bad news.