Buzz has it that Warner Bros. TV senior VP of drama development Nina Tassler has had talks with CBS about a high-level creative position at CBS Prods. Tassler, who worked with CBS Entertainment prexy Leslie Moonves when he was president of Warner Bros. TV, also has entertained other potential offers in recent weeks. Trouble is, though, she’s under contract at Warner Bros. until early next year, and the studio might fight to keep her until then. Meanwhile, Warner Bros. also is bringing two new execs into the fold: The studio just hired a new business affairs chief, and prexy Tony Jonas is in talks with Witt-Thomas president Gary Levine for the No. 2 post. CBS and Warner Bros. declined to comment.