DALLAS -- Security details at Barack Obama's rally Wednesday stopped screening people for weapons at the front gates more than an hour before the Democratic presidential candidate took the stage at Reunion Arena.The order to put down the metal detectors and stop checking purses and laptop bags came as a surprise to several Dallas police officers who said they believed it was a lapse in security.Dallas Deputy Police Chief T.W. Lawrence, head of the Police Department's homeland security and special operations divisions, said the order -- apparently made by the U.S. Secret Service -- was meant to speed up the...