Director Adam Kahan discusses his documentary, “The Case of the Three Sided Dream,” about multi-instrumentalist Rahsaan Roland Kirk. Kirk was not only a musician but was also a fighter for racial equality and for fair treatment of disabled persons (he was made blind as an infant by a wrongly administered eye medication). He also started a political movement to get more jazz, which he called Black Classical Music, on television. At the apex of his career Rahsaan suffered a debilitating stroke, which left half of his body paralyzed, yet he continued to play, record and tour, with the use of only one hand, literally until the day he died. “The Case of the Three Sided Dream” is playing July 26 at Rooftop Films Brookfield Place (formerly World Financial Center).