Sloane Tanen is an author and artist working in the capricious mode that has propelled Kay Thompson, Josh Schwartz, and Tina Fey to cult status: adolescent angst for adults. On display at Washington Square Windows — an all-hours gallery–slash–window display that gives Bloomingdale’s a run for its window shoppers — are her chenille chicks in various postures of anxious frivolity. There’s something for everyone: the Blair Waldorfs, the Seth Cohens, and the Stewies of the world.