Word traveled through the neighborhood faster than a spilled glass of grape juice on the kitchen floor: 10-year-old Jason Goldwach would be allowed to decorate his new bedroom any way he wanted.

Kids came from all over, markers in hand, intent on transforming the ordinary, white-walled bedroom in the ordinary middle-class San Francisco house into something, well . . . cool."(My friend) Enrique had this idea of drawing on the closet door," says Jason, who's now 12. "Then it just sort of spread through the room . . . like a mold."

After his two-year adventure in "interior decorating," Jason has had it.

"He's getting tired of it," says the youngster's mother.

"It's so filled up, nothing stands out anymore," complains Jason of his living quarters, which now most closely resembles the inside of a Muni bus.

The family has decided to redo the "Graffiti Room." "It's been fun," says Jason's mother, an artist. "It's been a place where he could truthfully express himself. . . . Kids often have a lot more energy than can be expressed on a sheet of paper."

Next weekend some of Jason's energy will go into repainting his bedroom.

Kids' bedroom decoration never used to be a big deal: A wagon-wheel motif twin bed with a matching dresser from Sears and you were in business. But in these days of less space, less money and youngsters insisting on having a hand in their own room decor, things have gotten a bit more complicated.

Juvenile furniture manufacturers are trying to keep pace, offering new ideas for baby-boomers in the middle of their own baby boom:

-Convertible furniture, i.e. pieces that be can be changed. A crib becomes a settee. A highchair folds into an adult's chair. Pint-sized tables "grow" as kids grow.

-Modular furniture that can be set up to accommodate more units. Buy a bunk bed this year; next year bolt on a desk, a chest or even a slide.

-Dual-purpose furniture combines, for example, a bench and a toy box.

-Theme furniture, which includes pieces such as a bed in the shape of a racing car.

Almost all children's furniture dealers suggest getting them involved in bedroom decor.

One San Francisco toy and children's furniture store has gone so far as to hire an interior decorator/psychologist to give a seminar to show parents how to "co-design with their children," presumably without ending up with something reminiscent of the New York City subway.

"What parents usually do is try to create a room they always wanted as a child but never had," says psychologist Tony Torrice, who went into the field of interior design when he discovered limited job opportunities for child psychologists. "Dad wants basketball wallpaper and a racing car bedspread. Mom wants the Laura Ashley print. These are parents who usually say in the same breath, `How come your room is in such a mess?' "

"Kids who leave their room in a mess are usually trying to let their parent know they're upset. They feel that it's not their room," he suggests.