I saw a show or movie on HBO where a girl was put into a painting by an evil witch and was never seen again - anyone know what this is?

Not sure this is the one, but it could be the 1990 movie The Witches (http://www.imdb.com/title/tt0100944/), based on the Roald Dahl novel.

A note from Wikipedia: "In the book, the little girl that was turned into part of a large oil painting – a farmyard scene featuring a flock of ducks – owned by her parents was eating a large red apple, given to her on her way home from school by a mysterious woman, which got her into the painting. In the movie, it's unknown what the witch did to get her inside the painting; all that is shown on-screen is the girl taking a short cut home through an alleyway adjacent to the witch's house, and the witch suddenly emerging from hiding in an open doorway, grabbing the girl, and dragging her through the doorway and out of sight. The girl is called Solveg in the book, but for the movie is renamed Erica. In both the book and the movie, the girl constantly changes her position in the painting with no-one ever seeing it happen (despite always being only a motionless oil-painted figure), as well as growing older within the painting; eventually, many years after becoming trapped inside the painting, the girl – now a frail old woman – disappears from it altogether (presumably she died). "