nextFocus method
void
nextFocus()
Moves focus to the next focusable node in the scope.
Implementation
void nextFocus() {
final chain = _focusableNodes;
if (chain.isEmpty) return;
final current = _nodes[_currentIndex];
final chainIndex = chain.indexOf(current);
final nextChainIndex = (chainIndex + 1) % chain.length;
final target = chain[nextChainIndex];
final targetIndex = _nodes.indexOf(target);
_setFocusAtIndex(targetIndex);
}