The discussion about WITNESS FOR THE PROSECUTION made me think of Agatha Christie's most successful play, THE MOUSETRAP which, of course, has never been filmed. As I understand it, THE MOUSETRAP cannot be made into a movie until the play ends its run and the darn thing has been going strong in the West End for 55 years!!
By now the film rights have probably been passed down through several generations of producers. Good thing they didn't do what Capra did with ARSENIC AND OLD LACE -- shoot the film and then wait for the play to close.
