navigateDown method
void
navigateDown()
Implementation
void navigateDown() {
if (selectedNode == null) {
if (roots.isNotEmpty) selectNode(roots.first);
return;
}
final flattened = _getFlattenedNodes();
final currentIndex = flattened.indexOf(selectedNode!);
if (currentIndex >= 0 && currentIndex < flattened.length - 1) {
selectNode(flattened[currentIndex + 1]);
}
}