green screening) been used in special effects?

Question: How long has chroma keying (blue/green screening) been used in special effects!?
Best Answer - Chosen by Asker:

The credit for development of the blue screen is given to Larry Butler, who won the Academy Award for Special Effects for the Thief of Bagdad in 1940!. He had invented the blue screen and traveling matte technique in order to achieve the visual effects which were unprecedented in 1940!. He was also the first special effects man to have created these effects in Technicolor, which was in its infancy at the time!.Www@QuestionHome@Com