Alan Cumming celebrated his role in Broadway’s “Macbeth” at a chic dinner party at W Hotel Times Square’s Wow suite. We’re told Liza Minnelli toasted him, “To my good friend Alan. From ‘Eyes Wide Shut,’ which isn’t happening tonight, to ‘Cabaret.’ ” Another highlight of the evening, which drew Anderson Cooper and boyfriend Benjamin Maisani, Cynthia Nixon, Cynthia Rowley and Cyndi Lauper, was Cumming performing a spontaneous handstand.