Poland's Walesa says Grass owes Poles explanation By Natalia Reiter REUTERS 8:58 a.m. August 18, 2006 WARSAW – Polish Solidarity hero Lech Walesa urged German author Guenter Grass on Friday to prove that a confession about his membership in Hitler's SS was not just a marketing ploy to promote his new novel. The former Polish president also said he would give up his honorary citizenship of Poland's city of Gdansk, if Grass, also a holder of the same title, failed to explain why he decided to confess when his autobiography 'Peeling Onions' came out. 'If Grass will not address his...