TableView: incorrect update of focusedCell on navigating with ctrl-up/down

To reproduce, run example below and follow the steps as outlined.

The expected behaviour on ctrl-up/down would be:

- either the focusedCell is updated the same as when navigating with the undecorated nav keys
- or the focusedCell is kept on the cell where the ctrl-nav started (astonishingly the behaviour in win7 explorer)

Either way, the important part from a usability perspective is to _have_ a _cell_ that's focused, that is a target cell for starting an edit f.i. by F2.

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

import java.util.Locale;
import java.util.logging.Logger;

/**
 * Simple demo to demonstrate the focusedCell bug.
 *
 * To reproduce:
 *
 * - click into any cell: focusedCell has both row and column
 * - move around with arrow keys: focusedCell changes both row and column
 * according to the navigation (expected behaviour)
 * - move up/down with ctrl-up/down: focusedCell row
 * keeps updating according to navigation, column is set to null (bug)
 */
public class TableFocusedCell extends Application {
    private static final Logger LOG = Logger.getLogger(TableFocusedCell.class.getName());
    
    private final ObservableList<Locale> data = FXCollections.observableArrayList(Locale.getAvailableLocales());

    private final TableView<Locale> table = new TableView<>(data);

    @Override public void start(Stage stage) {
        stage.setTitle("Table FocusedCell Bug");
        // add a listener to see loosing the column
        table.getFocusModel().focusedCellProperty().addListener((p, oldValue, newValue)-> {
            LOG.info("old/new " + oldValue + "\n " + newValue);
        });
        TableColumn<Locale, String> language = new TableColumn<>(
                "Language");
        language.setCellValueFactory(new PropertyValueFactory<Locale, String>("displayLanguage"));
        TableColumn<Locale, String> country = new TableColumn<>("Country");
        country.setCellValueFactory(new PropertyValueFactory<>("country"));
        table.setItems(data);
        table.getColumns().addAll(language, country);
        Scene scene = new Scene(new BorderPane(table));
        stage.setScene(scene);
        stage.show();
    }

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