Under the direction of the wily postmodernist David Gordon, “The Roundheads and the Pointheads,” Bertolt Brecht’s 1931 Marxist parable about how politicians distract from the conflict between rich and poor by focussing on less important differences, takes on new life. Scenes from the biographies of Brecht and the composer Hanns Eisler are effectively integrated with their songs, and explanations of Brecht’s theatrical theories are but one of the ways those theories are playfully enacted. The ensemble, which includes Valda Setterfield and John Kelly, is so uniformly excellent, so charming, that the overriding effect is not alienation but pleasure.