CHICAGO - Twenty minutes into the performance of "The Best Man" at a Chicago theater, veteran stage actor Gene Janson, onstage with fellow performer David Darlow, unexpectedly put his head in his hands. When Darlow asked Janson if he was OK, "He replied that he was not," said James Bohnen, artistic director of the Remy Bumppo Theatre Company, which is producing the play. Darlow rushed off the stage to get help, and a nurse in the matinee audience came to Janson's aid. Janson, 72, was taken Wednesday to Lincoln Park Hospital, where he died shortly after of a heart attack,...