Use the TOC tab to customize the Contents tab.
Border: Adds a border around the Contents pane.
Dialog Frame: Adds a frame around Contents pane.
Lines from Root: Displays lines connecting books and pages starting at root.
Folders instead of books: For table of contents book items, displays a folder icon in place of a book icon.
Single-Click to Open Book: Formats book items to open with a single click. When this feature is not selected, books open with a double-click.
Lines Between Items: Adds lines between books and pages.
Raised Edge: Formats the table of contents so it looks "raised" from the tri-pane (giving it a 3-D effect).
Sunken Edge: Formats the table of contents so it it looks "sunken" into the tri-pane (giving it a 3-D effect).