The policy used to move the focus from one focus node to another when traversing them using a keyboard.
If not specified, traverses in reading order using ReadingOrderTraversalPolicy.
- FocusTraversalPolicy for the API used to impose traversal order policy.
- WidgetOrderTraversalPolicy for a traversal policy that traverses nodes in the order they are added to the widget tree.
- ReadingOrderTraversalPolicy for a traversal policy that traverses nodes in the reading order defined in the widget tree, and then top to bottom.
final FocusTraversalPolicy policy;