My Book Idea [I Want to Write a Book]

It's about a man who's writing a children's book, but the characters within the story are living out their lives unbeknownst to him. When he takes a break, the world in the story just stops, including time. When the writer falls ill and can't return to the story, chaos breaks loose in the book world. I'm doing it. I'm writing this story.

If this idea isn't new, I'll tweak it.