Build a navtree section-group node.
Group nodes render as a dense uppercase label with their children always
visible at the same visual level (disposition='group'). The space is stored
in properties so child connectors can retrieve it without an extra graph lookup.
Build a navtree section-group node. Group nodes render as a dense uppercase label with their children always visible at the same visual level (disposition='group'). The space is stored in properties so child connectors can retrieve it without an extra graph lookup.