06/03/2011 AT 03:00 PM EDT
came out to support estranged hubby David Arquette
at his Beacher's Madhouse bash
inside the Hollywood Roosevelt Hotel
– and the two spent plenty of time together. The Cougar Town
star was one of the first guests to arrive, and took in the vaudeville show from the front row. At one point, Cox, who was sipping on vodka drinks, danced with Arquette on a ledge as she sang along to the music. Says an onlooker, "They looked so comfortable together – and like there was still a spark."