Created for a kids interactive (novel) adventure story so bear with the silliness :)
A tiddler for a "graphical" ToC, tagged to display in the right sidebar.
This is done with div's, borders, reveals and list filter/display. I couldn't use anything fancy like border/background colors, images, transparencies or gradients since my system/browser theme negates such things. Screenshots of just the right side bar/tabs window.
The first image shows the ToC default appearance-- closed till clicked on. Both "plaques" and the "handle" are clickable and have mouse hover over tooltips identifying what they do. The mouse pointer isn't showing in the screenshot but you can see the tooltip for the mouse hover over right under the "handle".

The second image is the ToC opened, showing the actual ToC. It's 2 images joined into one since the graphic part of the ToC scrolls off the page and can't be shown in a single screenshot.

Another mouse click on a "plaque" or the "handle" makes the ToC collaspe/close back to the first screenshot image.
Feel free to use, I will be posting the code and the tiddler with the code in a followup post-- going to see if I can make the CSS embedded into the tiddler with a <style> section. This would be for users who don't wish to or haven't learned how to add custom stylesheets yet.