Readings: White as...?

I was moved and disturbed by the following childhood anecdote concerning one of the six central characters in Karen Joy Fowler’s novel, The Jane Austen Book Club:

One day when she was four years old, while leafing through Sylvia’s beauty magazines, Allegra had taken offense at how much white space she found. “I don’t like white,” she’d said. “It’s so plain.” She burst into tears. “It’s so plain and there’s so much of it.” She sat for more than an hour, sobbing, working her way through the pages, coloring in the whites of people’s eyes, their teeth, the spaces between paragraphs, the frames around ads. She was sobbing because she could see that she would never be done; her whole life would be used up in the hopeless, endless task of amending this single lapse in taste. She would grow old, and there would still be white sheets, white walls, her own white hair.

What do you think “white” is a metaphor for here?