TreeView FocusModel focusing wrong index

Selecting the first entry and pressing the button raises the issue that the focus moves downwards while the selection is still correct.

public class GuiTestMainFocus extends Application {

    @Override
    public void start(Stage primaryStage) {
        Button btn = new Button();

        final TreeItem<String> treeItem = new TreeItem("Items");
        List<String> stringList = new ArrayList<String>();
        for (Integer i = 0; i < 10; i++) {
            stringList.add("Test " + i);
        }

        TreeView<String> treeView = new TreeView(treeItem);

        btn.setText("Set new list and select oldIdx!");
        btn.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                List<String> stringList = new ArrayList<String>();
                for (Integer i = 0; i < 10; i++) {
                    stringList.add("Changed " + i);
                }

                Integer oldIdx = treeView.getSelectionModel().getSelectedIndex();

                List<TreeItem<String>> treeItems = new ArrayList<>();
                stringList.forEach( p -> treeItems.add(new TreeItem(p)));

                treeView.getRoot().getChildren().setAll(treeItems);
                treeView.getSelectionModel().select(oldIdx);
                treeView.requestFocus();
            }
        });

        stringList.forEach(string -> treeItem.getChildren().add(new TreeItem(string)));
        HBox root = new HBox();
        treeView.setShowRoot(false);
        root.getChildren().addAll(treeView, btn);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}