It's impact or compression damage to the liquid crystal display, seen this many times on laptops owned by kids, dropping something on it, throwing something at it,(accidentally) it dropping off the desk or even sitting something heavy on the top of it can cause this, (on the newer thinbooks) a new LCD top end would cost almost as much as a new one now days with all the Xmas deals going on.
A CCFL type screen is an older unit, it may be time for a nice Xmas gift in the stocking.