Just downloaded Poser 13 trial and it does the same thing. In Poser 11 Library list acted the same as any windows list or file explorer. At the folder level typing the first letter of a folder name would take you to that folder. After expanding the folder, if the list was long typing the first letter again would take to that list item. So it wouldn't make any difference whether you were at the folder level or item level, typing the first letter would speed up the list search.