The line for Rainbow Rowell and David Levithan’s book signing at Brookline Booksmith on Monday night was so long it stretched between two floors. Rowell, a former columnist at the Omaha World-Herald, was out promoting her new book, “Fangirl,” while Levithan is touring with “Two Boys Kissing,” a novel that made the longlist for the National Book Award. Authors Paul Rudnick and Bill Konigsberg also read from their respective books, “Gorgeous” and “Openly Straight,” at the event. Rowell tweeted after the festivities: “I heard Tom Felton was in Boston yesterday. Think this is the 4th time I’ve shared a city with Felton. We’re 2 ships that pass in the night.” (Felton, a.k.a. Draco Malfoy from the “Harry Potter” films, was in town for Super Megafest, a fan convention at the Sheraton Framingham Hotel & Conference Center.) . . . In other young adult book news, Elaine Dimopoulos, the Boston Public Library’s Children’s Writer-in-Residence for 2010-11, got herself a book deal. Houghton Mifflin Harcourt picked up her project “Eco-Chic,” which Dimopoulos has described as a “Brave New World” and “Project Runway”-inspired tale about a young pop star and a fashion maven who are the gatekeepers of their society’s culture. The book will be released in spring 2015.