The on-again, off-again performance of a play by drama students at Shorewood High School has been canceled a second time. Students had planned to offer a closed performance for their parents yesterday, but that was called off after a heated Tuesday night meeting. A 17-year-old boy was arrested Wednesday for posting a threatening message online. The school district called the play off the first time for fear there would be protests over the inclusion of the “N-word” in the dialogue of “To Kill A Mockingbird.”