Pumpkin King Danny Elfman is coming to Barclays Center in Brooklyn on December 6 and 7 to perform his legendary role of Jack Skellington in a very special screening, with the music performed live by a full orchestra and choir, of Disney’s timeless holiday classic, “TIM BURTON’S THE NIGHTMARE BEFORE CHRISTMAS.” Elfman will be joined by other original cast members, including Catherine O’Hara (Sally) and Ken Page (Oogie Boogie), who will all sing live during the movie.    Tickets go on sale starting Friday, October 6 at 10:00am at www.barclayscenter.com or www.ticketmaster.com, or by phone at 800-745-3000. Tickets can also be purchased at the American Express Box Office at Barclays Center beginning Saturday, October 7 at noon…