/*
 * Copyright (c) 2010, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javafx.scene.control.skin;

import com.sun.javafx.scene.NodeHelper;
import com.sun.javafx.scene.ParentHelper;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.sun.javafx.scene.control.behavior.BehaviorBase;
import com.sun.javafx.scene.traversal.Algorithm;
import com.sun.javafx.scene.traversal.ParentTraversalEngine;
import com.sun.javafx.scene.traversal.TraversalContext;

import javafx.beans.property.ObjectProperty;
import javafx.beans.property.DoubleProperty;
import javafx.beans.value.WritableValue;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.geometry.HPos;
import javafx.geometry.Orientation;
import javafx.geometry.Pos;
import javafx.geometry.Side;
import javafx.geometry.VPos;
import javafx.scene.AccessibleAction;
import javafx.scene.AccessibleAttribute;
import javafx.scene.AccessibleRole;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.Control;
import javafx.scene.control.MenuItem;
import javafx.scene.control.CustomMenuItem;
import javafx.scene.control.Separator;
import javafx.scene.control.SeparatorMenuItem;
import javafx.scene.control.SkinBase;
import javafx.scene.control.ToolBar;
import javafx.scene.input.KeyCode;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.css.StyleableDoubleProperty;
import javafx.css.StyleableObjectProperty;
import javafx.css.StyleableProperty;
import javafx.css.CssMetaData;

import javafx.css.converter.EnumConverter;
import javafx.css.converter.SizeConverter;
import com.sun.javafx.scene.control.behavior.ToolBarBehavior;
import com.sun.javafx.scene.traversal.Direction;

import javafx.css.Styleable;

import static com.sun.javafx.scene.control.skin.resources.ControlResources.getString;

Default skin implementation for the ToolBar control. 
See Also:
ToolBar
Since:
9/**
 * Default skin implementation for the {@link ToolBar} control.
 *
 * @see ToolBar
 * @since 9
 */
public class ToolBarSkin extends SkinBase<ToolBar> {

    
                                                                        *
Private fields                                                          *
                                                                        *
/***************************************************************************
     *                                                                         *
     * Private fields                                                          *
     *                                                                         *
     **************************************************************************/

    private Pane box;
    private ToolBarOverflowMenu overflowMenu;
    private boolean overflow = false;
    private double previousWidth = 0;
    private double previousHeight = 0;
    private double savedPrefWidth = 0;
    private double savedPrefHeight = 0;
    private ObservableList<MenuItem> overflowMenuItems;
    private boolean needsUpdate = false;
    private final ParentTraversalEngine engine;
    private final BehaviorBase<ToolBar> behavior;



    /***************************************************************************
     *                                                                         *
     * Constructors                                                            *
     *                                                                         *
     **************************************************************************/

    
Creates a new ToolBarSkin instance, installing the necessary child nodes into the Control children list, as well as the necessary input mappings for handling key, mouse, etc events. 
Params:
control – The control that this skin should be installed onto./**
     * Creates a new ToolBarSkin instance, installing the necessary child
     * nodes into the Control {@link Control#getChildren() children} list, as
     * well as the necessary input mappings for handling key, mouse, etc events.
     *
     * @param control The control that this skin should be installed onto.
     */
    public ToolBarSkin(ToolBar control) {
        super(control);

        // install default input map for the ToolBar control
        behavior = new ToolBarBehavior(control);
//        control.setInputMap(behavior.getInputMap());

        overflowMenuItems = FXCollections.observableArrayList();
        initialize();
        registerChangeListener(control.orientationProperty(), e -> initialize());

        engine = new ParentTraversalEngine(getSkinnable(), new Algorithm() {

            private Node selectPrev(int from, TraversalContext context) {
                for (int i = from; i >= 0; --i) {
                    Node n = box.getChildren().get(i);
                    if (n.isDisabled() || !NodeHelper.isTreeShowing(n)) continue;
                    if (n instanceof Parent) {
                        Node selected = context.selectLastInParent((Parent)n);
                        if (selected != null) return selected;
                    }
                    if (n.isFocusTraversable() ) {
                        return n;
                    }
                }
                return null;
            }

            private Node selectNext(int from, TraversalContext context) {
                for (int i = from, max = box.getChildren().size(); i < max; ++i) {
                    Node n = box.getChildren().get(i);
                    if (n.isDisabled() || !NodeHelper.isTreeShowing(n)) continue;
                    if (n.isFocusTraversable()) {
                        return n;
                    }
                    if (n instanceof Parent) {
                        Node selected = context.selectFirstInParent((Parent)n);
                        if (selected != null) return selected;
                    }
                }
                return null;
            }

            @Override
            public Node select(Node owner, Direction dir, TraversalContext context) {
                final ObservableList<Node> boxChildren = box.getChildren();
                if (owner == overflowMenu) {
                    if (dir.isForward()) {
                        return null;
                    } else {
                        Node selected = selectPrev(boxChildren.size() - 1, context);
                        if (selected != null) return selected;
                    }
                }

                int idx = boxChildren.indexOf(owner);

                if (idx < 0) {
                    // The current focus owner is a child of some Toolbar's item
                    Parent item = owner.getParent();
                    while (!boxChildren.contains(item)) {
                        item = item.getParent();
                    }
                    Node selected = context.selectInSubtree(item, owner, dir);
                    if (selected != null) return selected;
                    idx = boxChildren.indexOf(item);
                    if (dir == Direction.NEXT) dir = Direction.NEXT_IN_LINE;
                }

                if (idx >= 0) {
                    if (dir.isForward()) {
                        Node selected = selectNext(idx + 1, context);
                        if (selected != null) return selected;
                        if (overflow) {
                            overflowMenu.requestFocus();
                            return overflowMenu;
                        }
                    } else {
                        Node selected = selectPrev(idx - 1, context);
                        if (selected != null) return selected;
                    }
                }
                return null;
            }

            @Override
            public Node selectFirst(TraversalContext context) {
                Node selected = selectNext(0, context);
                if (selected != null) return selected;
                if (overflow) {
                    return overflowMenu;
                }
                return null;
            }

            @Override
            public Node selectLast(TraversalContext context) {
                if (overflow) {
                    return overflowMenu;
                }
                return selectPrev(box.getChildren().size() - 1, context);
            }
        });
        ParentHelper.setTraversalEngine(getSkinnable(), engine);

        control.focusedProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue) {
                // TODO need to detect the focus direction
                // to selected the first control in the toolbar when TAB is pressed
                // or select the last control in the toolbar when SHIFT TAB is pressed.
                if (!box.getChildren().isEmpty()) {
                    box.getChildren().get(0).requestFocus();
                } else {
                    overflowMenu.requestFocus();
                }
            }
        });

        control.getItems().addListener((ListChangeListener<Node>) c -> {
            while (c.next()) {
                for (Node n: c.getRemoved()) {
                    box.getChildren().remove(n);
                }
                box.getChildren().addAll(c.getAddedSubList());
            }
            needsUpdate = true;
            getSkinnable().requestLayout();
        });
    }



    
                                                                        *
Properties                                                              *
                                                                        *
/***************************************************************************
     *                                                                         *
     * Properties                                                              *
     *                                                                         *
     **************************************************************************/

    private double snapSpacing(double value) {
        if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
            return snapSpaceY(value);
        } else {
            return snapSpaceX(value);
        }
    }

    // --- spacing
    private DoubleProperty spacing;
    private final void setSpacing(double value) {
        spacingProperty().set(snapSpacing(value));
    }

    private final double getSpacing() {
        return spacing == null ? 0.0 : snapSpacing(spacing.get());
    }

    private final DoubleProperty spacingProperty() {
        if (spacing == null) {
            spacing = new StyleableDoubleProperty() {

                @Override
                protected void invalidated() {
                    final double value = get();
                    if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                        ((VBox)box).setSpacing(value);
                    } else {
                        ((HBox)box).setSpacing(value);
                    }
                }

                @Override
                public Object getBean() {
                    return ToolBarSkin.this;
                }

                @Override
                public String getName() {
                    return "spacing";
                }

                @Override
                public CssMetaData<ToolBar,Number> getCssMetaData() {
                    return StyleableProperties.SPACING;
                }
            };
        }
        return spacing;
    }

    // --- box alignment
    private ObjectProperty<Pos> boxAlignment;
    private final void setBoxAlignment(Pos value) {
        boxAlignmentProperty().set(value);
    }

    private final Pos getBoxAlignment() {
        return boxAlignment == null ? Pos.TOP_LEFT : boxAlignment.get();
    }

    private final ObjectProperty<Pos> boxAlignmentProperty() {
        if (boxAlignment == null) {
            boxAlignment = new StyleableObjectProperty<Pos>(Pos.TOP_LEFT) {

                @Override
                public void invalidated() {
                    final Pos value = get();
                    if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                        ((VBox)box).setAlignment(value);
                    } else {
                        ((HBox)box).setAlignment(value);
                    }
                }

                @Override
                public Object getBean() {
                    return ToolBarSkin.this;
                }

                @Override
                public String getName() {
                    return "boxAlignment";
                }

                @Override
                public CssMetaData<ToolBar,Pos> getCssMetaData() {
                    return StyleableProperties.ALIGNMENT;
                }
            };
        }
        return boxAlignment;
    }



    /***************************************************************************
     *                                                                         *
     * Public API                                                              *
     *                                                                         *
     **************************************************************************/

    
{@inheritDoc} /** {@inheritDoc} */
    @Override public void dispose() {
        super.dispose();

        if (behavior != null) {
            behavior.dispose();
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computeMinWidth(double height, double topInset, double rightInset, double bottomInset, double leftInset) {
        final ToolBar toolbar = getSkinnable();
        return toolbar.getOrientation() == Orientation.VERTICAL ?
            computePrefWidth(-1, topInset, rightInset, bottomInset, leftInset) :
            snapSizeX(overflowMenu.prefWidth(-1)) + leftInset + rightInset;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computeMinHeight(double width, double topInset, double rightInset, double bottomInset, double leftInset) {
        final ToolBar toolbar = getSkinnable();
        return toolbar.getOrientation() == Orientation.VERTICAL?
            snapSizeY(overflowMenu.prefHeight(-1)) + topInset + bottomInset :
            computePrefHeight(-1, topInset, rightInset, bottomInset, leftInset);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computePrefWidth(double height, double topInset, double rightInset, double bottomInset, double leftInset) {
        double prefWidth = 0;
        final ToolBar toolbar = getSkinnable();

        if (toolbar.getOrientation() == Orientation.HORIZONTAL) {
            for (Node node : toolbar.getItems()) {
                if (!node.isManaged()) continue;
                prefWidth += snapSizeX(node.prefWidth(-1)) + getSpacing();
            }
            prefWidth -= getSpacing();
        } else {
            for (Node node : toolbar.getItems()) {
                if (!node.isManaged()) continue;
                prefWidth = Math.max(prefWidth, snapSizeX(node.prefWidth(-1)));
            }
            if (toolbar.getItems().size() > 0) {
                savedPrefWidth = prefWidth;
            } else {
                prefWidth = savedPrefWidth;
            }
        }
        return leftInset + prefWidth + rightInset;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computePrefHeight(double width, double topInset, double rightInset, double bottomInset, double leftInset) {
        double prefHeight = 0;
        final ToolBar toolbar = getSkinnable();

        if(toolbar.getOrientation() == Orientation.VERTICAL) {
            for (Node node: toolbar.getItems()) {
                if (!node.isManaged()) continue;
                prefHeight += snapSizeY(node.prefHeight(-1)) + getSpacing();
            }
            prefHeight -= getSpacing();
        } else {
            for (Node node : toolbar.getItems()) {
                if (!node.isManaged()) continue;
                prefHeight = Math.max(prefHeight, snapSizeY(node.prefHeight(-1)));
            }
            if (toolbar.getItems().size() > 0) {
                savedPrefHeight = prefHeight;
            } else {
                prefHeight = savedPrefHeight;
            }
        }
        return topInset + prefHeight + bottomInset;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computeMaxWidth(double height, double topInset, double rightInset, double bottomInset, double leftInset) {
        return getSkinnable().getOrientation() == Orientation.VERTICAL ?
                snapSizeX(getSkinnable().prefWidth(-1)) : Double.MAX_VALUE;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected double computeMaxHeight(double width, double topInset, double rightInset, double bottomInset, double leftInset) {
        return getSkinnable().getOrientation() == Orientation.VERTICAL ?
                Double.MAX_VALUE : snapSizeY(getSkinnable().prefHeight(-1));
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected void layoutChildren(final double x,final double y,
            final double w, final double h) {
//        super.layoutChildren();
        final ToolBar toolbar = getSkinnable();

        double toolbarLength = getToolbarLength(toolbar);
        if (toolbar.getOrientation() == Orientation.VERTICAL) {
            if (snapSizeY(toolbar.getHeight()) != previousHeight || needsUpdate) {
                ((VBox)box).setSpacing(getSpacing());
                ((VBox)box).setAlignment(getBoxAlignment());
                previousHeight = snapSizeY(toolbar.getHeight());
                addNodesToToolBar();
            } else {
                correctOverflow(toolbarLength);
            }
        } else {
            if (snapSizeX(toolbar.getWidth()) != previousWidth || needsUpdate) {
                ((HBox)box).setSpacing(getSpacing());
                ((HBox)box).setAlignment(getBoxAlignment());
                previousWidth = snapSizeX(toolbar.getWidth());
                addNodesToToolBar();
            } else {
                correctOverflow(toolbarLength);
            }
        }

        needsUpdate = false;

        double toolbarWidth = w;
        double toolbarHeight = h;

        if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
            toolbarHeight -= (overflow ? snapSizeY(overflowMenu.prefHeight(-1)) : 0);
        } else {
            toolbarWidth -= (overflow ? snapSizeX(overflowMenu.prefWidth(-1)) : 0);
        }

        box.resize(toolbarWidth, toolbarHeight);
        positionInArea(box, x, y,
                toolbarWidth, toolbarHeight, /*baseline ignored*/0, HPos.CENTER, VPos.CENTER);

        // If popup menu is not null show the overflowControl
        if (overflow) {
            double overflowMenuWidth = snapSizeX(overflowMenu.prefWidth(-1));
            double overflowMenuHeight = snapSizeY(overflowMenu.prefHeight(-1));
            double overflowX = x;
            double overflowY = x;
            if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                // This is to prevent the overflow menu from moving when there
                // are no items in the toolbar.
                if (toolbarWidth == 0) {
                    toolbarWidth = savedPrefWidth;
                }
                HPos pos = ((VBox)box).getAlignment().getHpos();
                if (HPos.LEFT.equals(pos)) {
                    overflowX = x + Math.abs((toolbarWidth - overflowMenuWidth)/2);
                } else if (HPos.RIGHT.equals(pos)) {
                    overflowX = (snapSizeX(toolbar.getWidth()) - snappedRightInset() - toolbarWidth) +
                        Math.abs((toolbarWidth - overflowMenuWidth)/2);
                } else {
                    overflowX = x +
                        Math.abs((snapSizeX(toolbar.getWidth()) - (x) +
                        snappedRightInset() - overflowMenuWidth)/2);
                }
                overflowY = snapSizeY(toolbar.getHeight()) - overflowMenuHeight - y;
            } else {
                // This is to prevent the overflow menu from moving when there
                // are no items in the toolbar.
                if (toolbarHeight == 0) {
                    toolbarHeight = savedPrefHeight;
                }
                VPos pos = ((HBox)box).getAlignment().getVpos();
                if (VPos.TOP.equals(pos)) {
                    overflowY = y +
                        Math.abs((toolbarHeight - overflowMenuHeight)/2);
                } else if (VPos.BOTTOM.equals(pos)) {
                    overflowY = (snapSizeY(toolbar.getHeight()) - snappedBottomInset() - toolbarHeight) +
                        Math.abs((toolbarHeight - overflowMenuHeight)/2);
                } else {
                    overflowY = y + Math.abs((toolbarHeight - overflowMenuHeight)/2);
                }
               overflowX = snapSizeX(toolbar.getWidth()) - overflowMenuWidth - snappedRightInset();
            }
            overflowMenu.resize(overflowMenuWidth, overflowMenuHeight);
            positionInArea(overflowMenu, overflowX, overflowY, overflowMenuWidth, overflowMenuHeight, /*baseline ignored*/0,
                    HPos.CENTER, VPos.CENTER);
        }
    }

    
                                                                        *
Private implementation                                                  *
                                                                        *
/***************************************************************************
     *                                                                         *
     * Private implementation                                                  *
     *                                                                         *
     **************************************************************************/

    private void initialize() {
        if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
            box = new VBox();
        } else {
            box = new HBox();
        }
        box.getStyleClass().add("container");
        box.getChildren().addAll(getSkinnable().getItems());
        overflowMenu = new ToolBarOverflowMenu(overflowMenuItems);
        overflowMenu.setVisible(false);
        overflowMenu.setManaged(false);

        getChildren().clear();
        getChildren().add(box);
        getChildren().add(overflowMenu);

        previousWidth = 0;
        previousHeight = 0;
        savedPrefWidth = 0;
        savedPrefHeight = 0;
        needsUpdate = true;
        getSkinnable().requestLayout();
    }

    private void correctOverflow(double length) {
        boolean overflowed = isOverflowed(length);
        if (overflowed != overflow) {
            organizeOverflow(length, overflow);
        }
    }

    private void organizeOverflow(double length, boolean hasOverflow) {
        if (hasOverflow) {
            if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                length -= snapSizeY(overflowMenu.prefHeight(-1));
            } else {
                length -= snapSizeX(overflowMenu.prefWidth(-1));
            }
            length -= getSpacing();
        }

        // Determine which node goes to the toolbar and which goes to the overflow.

        double x = 0;
        overflowMenuItems.clear();
        box.getChildren().clear();
        for (Node node : getSkinnable().getItems()) {
            node.getStyleClass().remove("menu-item");
            node.getStyleClass().remove("custom-menu-item");

            if (node.isManaged()) {
                if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                    x += snapSizeY(node.prefHeight(-1)) + getSpacing();
                } else {
                    x += snapSizeX(node.prefWidth(-1)) + getSpacing();
                }
            }

            if (x <= length) {
                box.getChildren().add(node);
            } else {
                if (node.isFocused()) {
                    if (!box.getChildren().isEmpty()) {
                        Node last = engine.selectLast();
                        if (last != null) {
                            last.requestFocus();
                        }
                    } else {
                        overflowMenu.requestFocus();
                    }
                }
                if (node instanceof Separator) {
                    overflowMenuItems.add(new SeparatorMenuItem());
                } else {
                    CustomMenuItem customMenuItem = new CustomMenuItem(node);

                    // RT-36455:
                    // We can't be totally certain of all nodes, but for the
                    // most common nodes we can check to see whether we should
                    // hide the menu when the node is clicked on. The common
                    // case is for TextField or Slider.
                    // This list won't be exhaustive (there is no point really
                    // considering the ListView case), but it should try to
                    // include most common control types that find themselves
                    // placed in menus.
                    final String nodeType = node.getTypeSelector();
                    switch (nodeType) {
                        case "Button":
                        case "Hyperlink":
                        case "Label":
                            customMenuItem.setHideOnClick(true);
                            break;
                        case "CheckBox":
                        case "ChoiceBox":
                        case "ColorPicker":
                        case "ComboBox":
                        case "DatePicker":
                        case "MenuButton":
                        case "PasswordField":
                        case "RadioButton":
                        case "ScrollBar":
                        case "ScrollPane":
                        case "Slider":
                        case "SplitMenuButton":
                        case "SplitPane":
                        case "TextArea":
                        case "TextField":
                        case "ToggleButton":
                        case "ToolBar":
                        default:
                            customMenuItem.setHideOnClick(false);
                            break;
                    }

                    overflowMenuItems.add(customMenuItem);
                }
            }
        }

        // Check if we overflowed.
        overflow = overflowMenuItems.size() > 0;
        if (!overflow && overflowMenu.isFocused()) {
            Node last = engine.selectLast();
            if (last != null) {
                last.requestFocus();
            }
        }
        overflowMenu.setVisible(overflow);
        overflowMenu.setManaged(overflow);
    }

    private void addNodesToToolBar() {
        final ToolBar toolbar = getSkinnable();
        double toolbarLength = getToolbarLength(toolbar);

        // Is there overflow ?
        boolean hasOverflow = isOverflowed(toolbarLength);

        organizeOverflow(toolbarLength, hasOverflow);
    }

    private double getToolbarLength(ToolBar toolbar) {
        double length;
        if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
            length = snapSizeY(toolbar.getHeight()) - snappedTopInset() - snappedBottomInset() + getSpacing();
        } else {
            length = snapSizeX(toolbar.getWidth()) - snappedLeftInset() - snappedRightInset() + getSpacing();
        }
        return length;
    }

    private boolean isOverflowed(double length) {
        double x = 0;
        boolean hasOverflow = false;
        for (Node node : getSkinnable().getItems()) {
            if (!node.isManaged()) continue;
            if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                x += snapSizeY(node.prefHeight(-1)) + getSpacing();
            } else {
                x += snapSizeX(node.prefWidth(-1)) + getSpacing();
            }
            if (x > length) {
                hasOverflow = true;
                break;
            }
        }
        return hasOverflow;
    }

    
                                                                        *
Support classes                                                         *
                                                                        *
/***************************************************************************
     *                                                                         *
     * Support classes                                                         *
     *                                                                         *
     **************************************************************************/

    class ToolBarOverflowMenu extends StackPane {
        private StackPane downArrow;
        private ContextMenu popup;
        private ObservableList<MenuItem> menuItems;

        public ToolBarOverflowMenu(ObservableList<MenuItem> items) {
            getStyleClass().setAll("tool-bar-overflow-button");
            setAccessibleRole(AccessibleRole.BUTTON);
            setAccessibleText(getString("Accessibility.title.ToolBar.OverflowButton"));
            setFocusTraversable(true);
            this.menuItems = items;
            downArrow = new StackPane();
            downArrow.getStyleClass().setAll("arrow");
            downArrow.setOnMousePressed(me -> {
                fire();
            });

            setOnKeyPressed(ke -> {
                if (KeyCode.SPACE.equals(ke.getCode())) {
                    if (!popup.isShowing()) {
                        popup.getItems().clear();
                        popup.getItems().addAll(menuItems);
                        popup.show(downArrow, Side.BOTTOM, 0, 0);
                    }
                    ke.consume();
                } else if (KeyCode.ESCAPE.equals(ke.getCode())) {
                    if (popup.isShowing()) {
                        popup.hide();
                    }
                    ke.consume();
                } else if (KeyCode.ENTER.equals(ke.getCode())) {
                    fire();
                    ke.consume();
                }
            });

            visibleProperty().addListener((observable, oldValue, newValue) -> {
                    if (newValue) {
                        if (box.getChildren().isEmpty()) {
                            setFocusTraversable(true);
                        }
                    }
            });
            popup = new ContextMenu();
            setVisible(false);
            setManaged(false);
            getChildren().add(downArrow);
        }

        private void fire() {
            if (popup.isShowing()) {
                popup.hide();
            } else {
                popup.getItems().clear();
                popup.getItems().addAll(menuItems);
                popup.show(downArrow, Side.BOTTOM, 0, 0);
            }
        }

        @Override protected double computePrefWidth(double height) {
            return snappedLeftInset() + snappedRightInset();
        }

        @Override protected double computePrefHeight(double width) {
            return snappedTopInset() + snappedBottomInset();
        }

        @Override protected void layoutChildren() {
            double w = snapSize(downArrow.prefWidth(-1));
            double h = snapSize(downArrow.prefHeight(-1));
            double x = (snapSize(getWidth()) - w)/2;
            double y = (snapSize(getHeight()) - h)/2;

            // TODO need to provide support for when the toolbar is on the right
            // or bottom
            if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
                downArrow.setRotate(0);
            }

            downArrow.resize(w, h);
            positionInArea(downArrow, x, y, w, h,
                    /*baseline ignored*/0, HPos.CENTER, VPos.CENTER);
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void executeAccessibleAction(AccessibleAction action, Object... parameters) {
            switch (action) {
                case FIRE: fire(); break;
                default: super.executeAccessibleAction(action); break;
            }
        }
    }

    
                                                                        *
                        Stylesheet Handling                             *
                                                                        *
/***************************************************************************
     *                                                                         *
     *                         Stylesheet Handling                             *
     *                                                                         *
     **************************************************************************/

     /*
      * Super-lazy instantiation pattern from Bill Pugh.
      */
     private static class StyleableProperties {
         private static final CssMetaData<ToolBar,Number> SPACING =
             new CssMetaData<ToolBar,Number>("-fx-spacing",
                 SizeConverter.getInstance(), 0.0) {

            @Override
            public boolean isSettable(ToolBar n) {
                final ToolBarSkin skin = (ToolBarSkin) n.getSkin();
                return skin.spacing == null || !skin.spacing.isBound();
            }

            @Override
            public StyleableProperty<Number> getStyleableProperty(ToolBar n) {
                final ToolBarSkin skin = (ToolBarSkin) n.getSkin();
                return (StyleableProperty<Number>)(WritableValue<Number>)skin.spacingProperty();
            }
        };

        private static final CssMetaData<ToolBar,Pos>ALIGNMENT =
                new CssMetaData<ToolBar,Pos>("-fx-alignment",
                new EnumConverter<Pos>(Pos.class), Pos.TOP_LEFT ) {

            @Override
            public boolean isSettable(ToolBar n) {
                final ToolBarSkin skin = (ToolBarSkin) n.getSkin();
                return skin.boxAlignment == null || !skin.boxAlignment.isBound();
            }

            @Override
            public StyleableProperty<Pos> getStyleableProperty(ToolBar n) {
                final ToolBarSkin skin = (ToolBarSkin) n.getSkin();
                return (StyleableProperty<Pos>)(WritableValue<Pos>)skin.boxAlignmentProperty();
            }
        };


         private static final List<CssMetaData<? extends Styleable, ?>> STYLEABLES;
         static {

            final List<CssMetaData<? extends Styleable, ?>> styleables =
                new ArrayList<CssMetaData<? extends Styleable, ?>>(SkinBase.getClassCssMetaData());

            // StackPane also has -fx-alignment. Replace it with
            // ToolBarSkin's.
            // TODO: Really should be able to reference StackPane.StyleableProperties.ALIGNMENT
            final String alignmentProperty = ALIGNMENT.getProperty();
            for (int n=0, nMax=styleables.size(); n<nMax; n++) {
                final CssMetaData<?,?> prop = styleables.get(n);
                if (alignmentProperty.equals(prop.getProperty())) styleables.remove(prop);
            }

            styleables.add(SPACING);
            styleables.add(ALIGNMENT);
            STYLEABLES = Collections.unmodifiableList(styleables);

         }
    }

    
Returns the CssMetaData associated with this class, which may include the
CssMetaData of its superclasses.
Returns:
the CssMetaData associated with this class, which may include the
CssMetaData of its superclasses/**
     * Returns the CssMetaData associated with this class, which may include the
     * CssMetaData of its superclasses.
     * @return the CssMetaData associated with this class, which may include the
     * CssMetaData of its superclasses
     */
    public static List<CssMetaData<? extends Styleable, ?>> getClassCssMetaData() {
        return StyleableProperties.STYLEABLES;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() {
        return getClassCssMetaData();
    }

    @Override
    protected Object queryAccessibleAttribute(AccessibleAttribute attribute, Object... parameters) {
        switch (attribute) {
            case OVERFLOW_BUTTON: return overflowMenu;
            default: return super.queryAccessibleAttribute(attribute, parameters);
        }
    }

    @Override
    protected void executeAccessibleAction(AccessibleAction action, Object... parameters) {
        switch (action) {
            case SHOW_MENU:
                overflowMenu.fire();
                break;
            default: super.executeAccessibleAction(action, parameters);
        }
    }
}