Mouse Interaction: Clicking an arc element expands it to reveal two additional levels.
If the selected element has child elements, focus automatically shifts to its first child.
If the selected element is a leaf (has no children), its label is added to the "Input Text" area,
and focus moves to the "Quick Keys" group on this keyboard.
Keyboard Interaction:
Press "j" to cycle through the rings from inner to outer.
Press "k" to cycle through the arcs within the current ring.
Press "Enter" to confirm the selection of an arc element, similar to a mouse click.