A diva ignores the scuttlebutt for the cause of a good party. Glamorous puss Chelsea Gibb stole the show (as a diva should) at the final night party for the hit musical Oh!  What a Night.     Gibb (pictured right ... er ... left with Gary Sweet) attended the final performance on the show before joining friends at the Amber Lounge in Lonsdale St for a private farewell to the production, which is heading to Sydney.     When last in town to star in the successful production of Anything Goes -- she was magnificent in the lead role -- Gibb was keeping very close to her towering partner Andrew Grace, a Sydney-based event organiser and great-grandson of the founder of Grace Bros department stores.     Grace, however, was conspicuously absent from Sunday night's celebrations -- and the hot rumour of the night was that the relationship was more than a little rocky.     In fact, Gibb declined to discuss him, preferring to chat animatedly with OWAN producer Michael Brereton and congratulate cast members on their terrific high-energy performances.     Since her Anything Goes visit, Gibb has completed a personal training course and is now qualified to whip people into shape.     Other cast members unwinding before heading to Sydney were Marcia Hines, who looked marvellous in a sexy Silvia Carr outfit and, of course, Gary Sweet.     Ralph Carr, fresh from ending a legal battle with former wife Tina Arena with a confidential out-of-court settlement, also popped in briefly for a drink.     Interesting to hear there has been a hotly contested series of social cricket matches between some of the stage shows playing in Melbourne in recent months.     The Singin' in the Rain gang took on the Mamma Mia! team, with Mamma Mia! prevailing.     Then the hot favourites from Oh!  What a Night took on Mamma Mia!.  In a boilover, the Mamma Mia! boys and girls easily outperformed the Oh!  What a Night crowd.