Make way for one more film festival, San Francisco. Premiering Wednesday with 28 features and shorts covering the core of Earth's health is the Green Screen Environmental Film Festival at the Castro Theatre. The festival, a project of San Francisco State University's Documentary Film Institute, will be part of the U.N. World Environment Day, coinciding with a meeting of mayors from around the world to brainstorm about urban environmental policies. Delfin Vigil reports in the San Francisco Chronicle.