The "Show All" button (toward the lower left side of the screen) allows you to repaint the left "Documents Available" panel to display every file in the parent folder. (The default display is the show just documents or glossary terms that meet the filtering criteria set in the "Libraries & Books" screen. This not only will display all documents that 'exceed' the filter, but it will also display non-document files such as Excel files and images that you have saved in the designated book. This in turn enables Excel and image assembly as well as paragraph and document assembly.