In addition to the letter and root, the contents tree can show the head word, head phrase (see here for an explanation) and node.
When check Roman numerals will be shown in tree.
Moving around the tree using the keyboard can be done using the up and down arrows. These two options provide additional movement keys.
The tree can be expanded/collapsed with the mouse or the keyboard using either the spacebar or the key set here.
To set either of the fonts click the button and choose the settings from font selection dialog.