Question: Who wrote a screenplay about a boy and a stray dog for Walt Disney?

Context paragraphs:
Walt Disney World Dolphin: The Walt Disney World Dolphin is a resort hotel designed by architect Michael Graves located between Epcot and Disney's Hollywood Studios in the Walt Disney World Resort in Bay Lake, Florida, next to Disney's BoardWalk Resort area.  It opened on June 1, 1990 and is joined to its sister hotel, the Walt Disney World Swan (also designed by Graves) by a palm-tree lined covered walkway crossing a lagoon.  The Walt Disney World Swan and Dolphin is a joint venture between the Walt Disney Company, Tishman Hotel Corporation, MetLife and Starwood Hotels and Resorts.  The land the resort occupies is owned by the Walt Disney Company, while the buildings themselves are leased by Disney to the Tishman Hotel Corporation and MetLife but operated by Starwood Hotels & Resorts Worldwide under the Sheraton Hotels brand.  The Walt Disney World Swan and Dolphin are a part of the Walt Disney Collection of resorts; because of this they are Disney branded and guests of the resort have access to special Disney benefits available to Disney Resort Hotel guests only.

Norakuro: Norakuro (のらくろ ) is a Japanese manga series created by Suihō Tagawa and published by Kodansha in "Shōnen Kurabu".  The titular protagonist, Norakuro, or Norakuro-"kun", is an anthropomorphic black and white dog.  The name "Norakuro" is an abbreviation of "norainu" (野良犬 , stray dog) and "Kurokichi" (黒吉 , the name of the dog, literally meaning "black lucky") .

Redemption: The No Kill Revolution in America: The film tells the story of Henry Bergh, a New Yorker who made it his mission to protect animals from cruelty after witnessing cruelty toward cart horses being used for transportation.  In 1866, he persuaded 100 people, including New York City's Mayor, to sign his Declaration of the Rights of Animals; with that step, founding the American Society for the Prevention of Cruelty to Animals.  For two decades, he worked hard tending to sick animals, ensuring that animal cruelty was prosecuted, and advocating for the city's stray dog population.  Before his death, he said, "I hate to think what will befall this Society when I am gone."  Against his express instructions, the ASPCA agreed to run the dog pound, trading its mission of protecting animals for the role of killing them, to the point where shelter killing has become the leading cause of death of healthy dogs and cats in the United States.

A Dog's Life: The Autobiography of a Stray: A Dog's Life: The Autobiography of a Stray is a children's novel written in 2005 by Ann M. Martin and is published by Scholastic Books.  The target audience for this book is grades 4-7.  It is written from the first-person perspective of a female stray dog named Squirrel.  Ann M. Martin bases her books on personal experiences and contemporary problems or events.

White Dog: White Dog is a 1982 American drama film, which Samuel Fuller directed from a screenplay he and Curtis Hanson had dramatized, which, in turn, they based loosely on Romain Gary's 1970 novel of the same title.  The film depicts the struggle of a dog trainer named Keys (Paul Winfield), who is black, trying to retrain a stray dog found by a young actress (Kristy McNichol), that is a "white dog"--a dog trained to make vicious attacks upon, and to murder, any black person.  Fuller uses the film as a platform to deliver an anti-racist message as it examines the question of whether racism is a treatable problem or an incurable condition.

Malchik: Malchik (Russian: Мальчик , 'Little Boy' ; 1996 – December 2001) was a black mongrel stray dog living in Moscow, Russia.  For about three years, Malchik lived at the Mendeleyevskaya station on the Moscow Metro.  Malchik became a popular station "resident" among rail employees and commuters, and defended his territory against drunks and other dogs.  Malchik was killed when a 22-year-old woman Yuliana Romanova stabbed him with a kitchen knife.  Later it was revealed that Romanova has a long history of cruelty to animals and psychiatric treatment.  The incident sparked a wave of public outrage regarding the treatment of animals, and, in 2007, a monument was erected in Malchik's honour at Mendeleyevskaya station.

Laika: Laika (Russian: Лайка ; c. 1954 – November 3, 1957) was a Soviet space dog who became one of the first animals in space, and the first animal to orbit the Earth.  Laika, a stray dog from the streets of Moscow, was selected to be the occupant of the Soviet spacecraft Sputnik 2 that was launched into outer space on November 3, 1957.

Stray Dog Café: The Stray Dog (Russian: Бродя́чая соба́ка ) (aka Stray Dog Cellar, Stray Dog Cabaret and the Society for Intimate Theatre) was located at Ploshchad Isskustv, Square of the Arts up to Summer Gardens, St. Petersburg, Russia.

William Tunberg (screenwriter): He wrote the screenplay for "Old Yeller" and "That's My Baby! ".  His son, Karl Alexander, was a writer too.  His brother, Karl Tunberg, wrote the screenplay for "Ben-Hur"—and worked on a number of films himself.

Old Yeller (film): Old Yeller is a 1957 American drama film produced by Walt Disney.  It stars Tommy Kirk, Dorothy McGuire and Beverly Washburn.  It is about a boy and a stray dog in post-Civil War Texas.  The film is based upon the 1956 Newbery Honor-winning book of the same name by Fred Gipson.  Gipson also cowrote the screenplay with William Tunberg.  The success of the "Old Yeller" film led to a sequel, "Savage Sam", which was also based on a book by Gipson.

Supporting paragraphs: William Tunberg (screenwriter) Old Yeller (film)
Answer: William Tunberg