Gays don't always have the best grasp on their activist history (which may be why they think that picketing a lame bar is the best use of their resources), but you couldn't ask for a better learning opportunity than "Screaming Queens: The Riot at Compton's Cafeteria," a recounting not only of the riot, but also of its social context. Today's party at Aunt Charlie's is happening because the film is premiering locally on KQED at 6:00 PM, so if you missed yesterday's packed showing at the Castro, now's your chance to catch it. In addition to collecting fascinating historical footage, hilariously middle-America newsreels, and historical documents, the film features a wealth of colorful interview subjects, such as the lone, gruff cop who reached out to the queer community, and a strong-willed entertainer who still performs at Aunt Charlie's. Those folks laid the foundation for future decades' civil rights battles, and create a vivid portrait of a neighborhood in which transgender people developed the strength to demand better.