"To steal the show" origin?

When someone or something steals the show, they are the unexpected focus of (positive) attention. If you go to a movie starring George Clooney, but realize afterward that all the scenes with a relatively unknown actress are the ones that you enjoyed most, you could say that the actress has stolen the show; you went with the expectation of enjoying George Clooney but found yourself largely ignoring him in favor of focusing on someone else entirely.