A loose adaptation (and riff on) Anton Chekhov’s “The Seagull.” Con is an aspiring playwright, frustrated with the state of the modern theatre. His mother, Emma, is a famous actress, whose commercial work he despises. What unfolds between them over the course of five years calls to mind questions about unrequited love, artistic integrity, and the passability of a seagull as a metaphor. Incorporating movement, audience interaction, and ukulele songs about nihilism, Posner’s new play is a fast, funny, and moving look at timeless themes with a fresh eye.