private TOCItem getSelectedItem(TreeSelectionEvent e, JHelpNavigator navigator) {
			TreePath newLeadSelectionPath = e.getNewLeadSelectionPath();
			if (newLeadSelectionPath == null) {
				navigator.setSelectedItems(null);
				return null;
			}

			DefaultMutableTreeNode node =
				(DefaultMutableTreeNode) newLeadSelectionPath.getLastPathComponent();
			TOCItem treeItem = (TOCItem) node.getUserObject();
			navigator.setSelectedItems(new TreeItem[] { treeItem });

			return treeItem;
		}
Our hook to install our custom cell renderer.
Ghidra/Framework/Help/src/main/java/help/CustomTOCView.java