Shelley Duvall, the intrepid, Texas-born movie star whose wide-eyed, winsome presence was a mainstay in the films of Robert Altman and who co-starred in Stanley Kubrick’s “The Shining,” has died. She was 75. Her longtime partner, Dan Gilroy, says Duvall died Thursday in her sleep at her home in Blanco, Texas. Her friend, the publicist Gary Springer, says the cause was complications of diabetes. Duvall was attending junior college in Texas when Altman’s staff members, preparing to film “Brewster McCloud,” encountered her as at a party in Houston in 1970. She would go on to become Altman’s protege.