src/java.desktop/share/classes/javax/swing/JRootPane.java - master - githubmirror/jdk22

src/java.desktop/share/classes/javax/swing/JRootPane.java
1 051 строка39 KB
Prasanta Sadhukhan
8282473: Refactor swing classes javadoc to use @throws instead of @exception
17 мар 2022, 12:10
17 мар 2022, 12:10096bca4
/*
 * Copyright (c) 1997, 2021, 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 javax.swing;

import java.awt.*;
import java.beans.*;
import java.security.AccessController;
import javax.accessibility.*;
import javax.swing.plaf.RootPaneUI;
import java.io.Serializable;

import sun.security.action.GetBooleanAction;


/**
 * A lightweight container used behind the scenes by
 * <code>JFrame</code>, <code>JDialog</code>, <code>JWindow</code>,
 * <code>JApplet</code>, and <code>JInternalFrame</code>.
 * For task-oriented information on functionality provided by root panes
 * see <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/rootpane.html">How to Use Root Panes</a>,
 * a section in <em>The Java Tutorial</em>.
 *
 * <p>
 * The following image shows the relationships between
 * the classes that use root panes.
 * <p style="text-align:center"><img src="doc-files/JRootPane-1.gif"
 * alt="The following text describes this graphic."
 * HEIGHT=484 WIDTH=629></p>
 * The &quot;heavyweight&quot; components (those that delegate to a peer, or native
 * component on the host system) are shown with a darker, heavier box. The four
 * heavyweight JFC/Swing containers (<code>JFrame</code>, <code>JDialog</code>,
 * <code>JWindow</code>, and <code>JApplet</code>) are
 * shown in relation to the AWT classes they extend.
 * These four components are the
 * only heavyweight containers in the Swing library. The lightweight container
 * <code>JInternalFrame</code> is also shown.
 * All five of these JFC/Swing containers implement the
 * <code>RootPaneContainer</code> interface,
 * and they all delegate their operations to a
 * <code>JRootPane</code> (shown with a little "handle" on top).
 * <blockquote>
 * <b>Note:</b> The <code>JComponent</code> method <code>getRootPane</code>
 * can be used to obtain the <code>JRootPane</code> that contains
 * a given component.
 * </blockquote>
 *
 * <div style="float:right;text-align:center;font-weight:bold">
 *   <p>Example:
 *   <p><img src="doc-files/JRootPane-2.gif"
 *      alt="the following text describes this graphic." height=386 width=349>
 * </div>
 * The diagram at right shows the structure of a <code>JRootPane</code>.
 * A <code>JRootpane</code> is made up of a <code>glassPane</code>,
 * an optional <code>menuBar</code>, and a <code>contentPane</code>.
 * (The <code>JLayeredPane</code> manages the <code>menuBar</code>
 * and the <code>contentPane</code>.)
 * The <code>glassPane</code> sits over the top of everything,
 * where it is in a position to intercept mouse movements.
 * Since the <code>glassPane</code> (like the <code>contentPane</code>)
 * can be an arbitrary component, it is also possible to set up the
 * <code>glassPane</code> for drawing. Lines and images on the
 * <code>glassPane</code> can then range
 * over the frames underneath without being limited by their boundaries.
 * <p>
 * Although the <code>menuBar</code> component is optional,
 * the <code>layeredPane</code>, <code>contentPane</code>,
 * and <code>glassPane</code> always exist.
 * Attempting to set them to <code>null</code> generates an exception.
 * <p>
 * To add components to the <code>JRootPane</code> (other than the
 * optional menu bar), you add the object to the <code>contentPane</code>
 * of the <code>JRootPane</code>, like this:
 * <pre>
 *       rootPane.getContentPane().add(child);
 * </pre>
 * The same principle holds true for setting layout managers, removing
 * components, listing children, etc. All these methods are invoked on
 * the <code>contentPane</code> instead of on the <code>JRootPane</code>.
 * <blockquote>
 * <b>Note:</b> The default layout manager for the <code>contentPane</code> is
 *  a <code>BorderLayout</code> manager. However, the <code>JRootPane</code>
 *  uses a custom <code>LayoutManager</code>.
 *  So, when you want to change the layout manager for the components you added
 *  to a <code>JRootPane</code>, be sure to use code like this:
 * <pre>
 *    rootPane.getContentPane().setLayout(new BoxLayout());
 * </pre></blockquote>
 * If a <code>JMenuBar</code> component is set on the <code>JRootPane</code>,
 * it is positioned along the upper edge of the frame.
 * The <code>contentPane</code> is adjusted in location and size to
 * fill the remaining area.
 * (The <code>JMenuBar</code> and the <code>contentPane</code> are added to the
 * <code>layeredPane</code> component at the
 * <code>JLayeredPane.FRAME_CONTENT_LAYER</code> layer.)
 * <p>
 * The <code>layeredPane</code> is the parent of all children in the
 * <code>JRootPane</code> -- both as the direct parent of the menu and
 * the grandparent of all components added to the <code>contentPane</code>.
 * It is an instance of <code>JLayeredPane</code>,
 * which provides the ability to add components at several layers.
 * This capability is very useful when working with menu popups,
 * dialog boxes, and dragging -- situations in which you need to place
 * a component on top of all other components in the pane.
 * <p>
 * The <code>glassPane</code> sits on top of all other components in the
 * <code>JRootPane</code>.
 * That provides a convenient place to draw above all other components,
 * and makes it possible to intercept mouse events,
 * which is useful both for dragging and for drawing.
 * Developers can use <code>setVisible</code> on the <code>glassPane</code>
 * to control when the <code>glassPane</code> displays over the other children.
 * By default the <code>glassPane</code> is not visible.
 * <p>
 * The custom <code>LayoutManager</code> used by <code>JRootPane</code>
 * ensures that:
 * <OL>
 * <LI>The <code>glassPane</code> fills the entire viewable
 *     area of the <code>JRootPane</code> (bounds - insets).
 * <LI>The <code>layeredPane</code> fills the entire viewable area of the
 *     <code>JRootPane</code>. (bounds - insets)
 * <LI>The <code>menuBar</code> is positioned at the upper edge of the
 *     <code>layeredPane</code>.
 * <LI>The <code>contentPane</code> fills the entire viewable area,
 *     minus the <code>menuBar</code>, if present.
 * </OL>
 * Any other views in the <code>JRootPane</code> view hierarchy are ignored.
 * <p>
 * If you replace the <code>LayoutManager</code> of the <code>JRootPane</code>,
 * you are responsible for managing all of these views.
 * So ordinarily you will want to be sure that you
 * change the layout manager for the <code>contentPane</code> rather than
 * for the <code>JRootPane</code> itself!
 * <p>
 * The painting architecture of Swing requires an opaque
 * <code>JComponent</code>
 * to exist in the containment hierarchy above all other components. This is
 * typically provided by way of the content pane. If you replace the content
 * pane, it is recommended that you make the content pane opaque
 * by way of <code>setOpaque(true)</code>. Additionally, if the content pane
 * overrides <code>paintComponent</code>, it
 * will need to completely fill in the background in an opaque color in
 * <code>paintComponent</code>.
 * <p>
 * <strong>Warning:</strong> Swing is not thread safe. For more
 * information see <a
 * href="package-summary.html#threading">Swing's Threading
 * Policy</a>.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @see JLayeredPane
 * @see JMenuBar
 * @see JWindow
 * @see JFrame
 * @see JDialog
 * @see JApplet
 * @see JInternalFrame
 * @see JComponent
 * @see BoxLayout
 *
 * @see <a href="http://www.oracle.com/technetwork/articles/java/mixing-components-433992.html">
 * Mixing Heavy and Light Components</a>
 *
 * @author David Kloba
 * @since 1.2
 */
/// PENDING(klobad) Who should be opaque in this component?
@SuppressWarnings("serial")
public class JRootPane extends JComponent implements Accessible {

    private static final String uiClassID = "RootPaneUI";

    /**
     * Whether or not we should dump the stack when true double buffering
     * is disabled. Default is false.
     */
    @SuppressWarnings("removal")
    private static final boolean LOG_DISABLE_TRUE_DOUBLE_BUFFERING
            = AccessController.doPrivileged(new GetBooleanAction(
                                   "swing.logDoubleBufferingDisable"));

    /**
     * Whether or not we should ignore requests to disable true double
     * buffering. Default is false.
     */
    @SuppressWarnings("removal")
    private static final boolean IGNORE_DISABLE_TRUE_DOUBLE_BUFFERING
            = AccessController.doPrivileged(new GetBooleanAction(
                                   "swing.ignoreDoubleBufferingDisable"));

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should not provide any sort of
     * Window decorations.
     *
     * @since 1.4
     */
    public static final int NONE = 0;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Frame.
     *
     * @since 1.4
     */
    public static final int FRAME = 1;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog.
     *
     * @since 1.4
     */
    public static final int PLAIN_DIALOG = 2;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to display an informational message.
     *
     * @since 1.4
     */
    public static final int INFORMATION_DIALOG = 3;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to display an error message.
     *
     * @since 1.4
     */
    public static final int ERROR_DIALOG = 4;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to display a <code>JColorChooser</code>.
     *
     * @since 1.4
     */
    public static final int COLOR_CHOOSER_DIALOG = 5;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to display a <code>JFileChooser</code>.
     *
     * @since 1.4
     */
    public static final int FILE_CHOOSER_DIALOG = 6;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to present a question to the user.
     *
     * @since 1.4
     */
    public static final int QUESTION_DIALOG = 7;

    /**
     * Constant used for the windowDecorationStyle property. Indicates that
     * the <code>JRootPane</code> should provide decorations appropriate for
     * a Dialog used to display a warning message.
     *
     * @since 1.4
     */
    public static final int WARNING_DIALOG = 8;

    private int windowDecorationStyle;

    /** The menu bar. */
    protected JMenuBar menuBar;

    /** The content pane. */
    protected Container contentPane;

    /** The layered pane that manages the menu bar and content pane. */
    protected JLayeredPane layeredPane;

    /**
     * The glass pane that overlays the menu bar and content pane,
     *  so it can intercept mouse movements and such.
     */
    protected Component glassPane;
    /**
     * The button that gets activated when the pane has the focus and
     * a UI-specific action like pressing the <b>Enter</b> key occurs.
     */
    protected JButton defaultButton;

    /**
     * Whether or not true double buffering should be used.  This is typically
     * true, but may be set to false in special situations.  For example,
     * heavy weight popups (backed by a window) set this to false.
     */
    boolean useTrueDoubleBuffering = true;

    /**
     * Creates a <code>JRootPane</code>, setting up its
     * <code>glassPane</code>, <code>layeredPane</code>,
     * and <code>contentPane</code>.
     */
    public JRootPane() {
        setGlassPane(createGlassPane());
        setLayeredPane(createLayeredPane());
        setContentPane(createContentPane());
        setLayout(createRootLayout());
        setDoubleBuffered(true);
        updateUI();
    }

    /**
     * {@inheritDoc}
     * @since 1.6
     */
    public void setDoubleBuffered(boolean aFlag) {
        if (isDoubleBuffered() != aFlag) {
            super.setDoubleBuffered(aFlag);
            RepaintManager.currentManager(this).doubleBufferingChanged(this);
        }
    }

    /**
     * Returns a constant identifying the type of Window decorations the
     * <code>JRootPane</code> is providing.
     *
     * @return One of <code>NONE</code>, <code>FRAME</code>,
     *        <code>PLAIN_DIALOG</code>, <code>INFORMATION_DIALOG</code>,
     *        <code>ERROR_DIALOG</code>, <code>COLOR_CHOOSER_DIALOG</code>,
     *        <code>FILE_CHOOSER_DIALOG</code>, <code>QUESTION_DIALOG</code> or
     *        <code>WARNING_DIALOG</code>.
     * @see #setWindowDecorationStyle
     * @since 1.4
     */
    public int getWindowDecorationStyle() {
        return windowDecorationStyle;
    }

    /**
     * Sets the type of Window decorations (such as borders, widgets for
     * closing a Window, title ...) the <code>JRootPane</code> should
     * provide. The default is to provide no Window decorations
     * (<code>NONE</code>).
     * <p>
     * This is only a hint, and some look and feels may not support
     * this.
     * This is a bound property.
     *
     * @param windowDecorationStyle Constant identifying Window decorations
     *        to provide.
     * @see JDialog#setDefaultLookAndFeelDecorated
     * @see JFrame#setDefaultLookAndFeelDecorated
     * @see LookAndFeel#getSupportsWindowDecorations
     * @throws IllegalArgumentException if <code>style</code> is
     *        not one of: <code>NONE</code>, <code>FRAME</code>,
     *        <code>PLAIN_DIALOG</code>, <code>INFORMATION_DIALOG</code>,
     *        <code>ERROR_DIALOG</code>, <code>COLOR_CHOOSER_DIALOG</code>,
     *        <code>FILE_CHOOSER_DIALOG</code>, <code>QUESTION_DIALOG</code>, or
     *        <code>WARNING_DIALOG</code>.
     * @since 1.4
     */
    @BeanProperty(expert = true, visualUpdate = true, enumerationValues = {
            "JRootPane.NONE",
            "JRootPane.FRAME",
            "JRootPane.PLAIN_DIALOG",
            "JRootPane.INFORMATION_DIALOG",
            "JRootPane.ERROR_DIALOG",
            "JRootPane.COLOR_CHOOSER_DIALOG",
            "JRootPane.FILE_CHOOSER_DIALOG",
            "JRootPane.QUESTION_DIALOG",
            "JRootPane.WARNING_DIALOG"}, description
            = "Identifies the type of Window decorations to provide")
    public void setWindowDecorationStyle(int windowDecorationStyle) {
        if (windowDecorationStyle < 0 ||
                  windowDecorationStyle > WARNING_DIALOG) {
            throw new IllegalArgumentException("Invalid decoration style");
        }
        int oldWindowDecorationStyle = getWindowDecorationStyle();
        this.windowDecorationStyle = windowDecorationStyle;
        firePropertyChange("windowDecorationStyle",
                            oldWindowDecorationStyle,
                            windowDecorationStyle);
    }

    /**
     * Returns the L&amp;F object that renders this component.
     *
     * @return <code>LabelUI</code> object
     * @since 1.3
     */
    public RootPaneUI getUI() {
        return (RootPaneUI)ui;
    }

    /**
     * Sets the L&amp;F object that renders this component.
     *
     * @param ui  the <code>LabelUI</code> L&amp;F object
     * @see UIDefaults#getUI
     * @since 1.3
     */
    @BeanProperty(expert = true, hidden = true, visualUpdate = true, description
            = "The UI object that implements the Component's LookAndFeel.")
    public void setUI(RootPaneUI ui) {
        super.setUI(ui);
    }


    /**
     * Resets the UI property to a value from the current look and feel.
     *
     * @see JComponent#updateUI
     */
    public void updateUI() {
        setUI((RootPaneUI)UIManager.getUI(this));
    }


    /**
     * Returns a string that specifies the name of the L&amp;F class
     * that renders this component.
     *
     * @return the string "RootPaneUI"
     *
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }

    /**
      * Called by the constructor methods to create the default
      * <code>layeredPane</code>.
      * Bt default it creates a new <code>JLayeredPane</code>.
      * @return the default <code>layeredPane</code>
      */
    protected JLayeredPane createLayeredPane() {
        JLayeredPane p = new JLayeredPane();
        p.setName(this.getName()+".layeredPane");
        return p;
    }

    /**
     * Called by the constructor methods to create the default
     * <code>contentPane</code>.
     * By default this method creates a new <code>JComponent</code> add sets a
     * <code>BorderLayout</code> as its <code>LayoutManager</code>.
     * @return the default <code>contentPane</code>
     */
    protected Container createContentPane() {
        JComponent c = new JPanel();
        c.setName(this.getName()+".contentPane");
        c.setLayout(new BorderLayout() {
            /* This BorderLayout subclass maps a null constraint to CENTER.
             * Although the reference BorderLayout also does this, some VMs
             * throw an IllegalArgumentException.
             */
            public void addLayoutComponent(Component comp, Object constraints) {
                if (constraints == null) {
                    constraints = BorderLayout.CENTER;
                }
                super.addLayoutComponent(comp, constraints);
            }
        });
        return c;
    }

    /**
      * Called by the constructor methods to create the default
      * <code>glassPane</code>.
      * By default this method creates a new <code>JComponent</code>
      * with visibility set to false.
      * @return the default <code>glassPane</code>
      */
    protected Component createGlassPane() {
        JPanel c = new JPanel();
        c.setName(this.getName()+".glassPane");
        c.setVisible(false);
        c.setOpaque(false);
        return c;
    }

    /**
     * Called by the constructor methods to create the default
     * <code>layoutManager</code>.
     * @return the default <code>layoutManager</code>.
     */
    protected LayoutManager createRootLayout() {
        return new RootLayout();
    }

    /**
     * Adds or changes the menu bar used in the layered pane.
     * @param menu the <code>JMenuBar</code> to add
     */
    public void setJMenuBar(JMenuBar menu) {
        if(menuBar != null && menuBar.getParent() == layeredPane)
            layeredPane.remove(menuBar);
        menuBar = menu;

        if(menuBar != null) {
            menuBar.updateUI();
            layeredPane.add(menuBar, JLayeredPane.FRAME_CONTENT_LAYER);
        }
    }

    /**
     * Specifies the menu bar value.
     * @deprecated As of Swing version 1.0.3
     *  replaced by <code>setJMenuBar(JMenuBar menu)</code>.
     * @param menu the <code>JMenuBar</code> to add.
     */
    @Deprecated
    public void setMenuBar(JMenuBar menu){
        if(menuBar != null && menuBar.getParent() == layeredPane)
            layeredPane.remove(menuBar);
        menuBar = menu;

        if(menuBar != null)
            layeredPane.add(menuBar, JLayeredPane.FRAME_CONTENT_LAYER);
    }

    /**
     * Returns the menu bar from the layered pane.
     * @return the <code>JMenuBar</code> used in the pane
     */
    public JMenuBar getJMenuBar() { return menuBar; }

    /**
     * Returns the menu bar value.
     * @deprecated As of Swing version 1.0.3
     *  replaced by <code>getJMenuBar()</code>.
     * @return the <code>JMenuBar</code> used in the pane
     */
    @Deprecated
    public JMenuBar getMenuBar() { return menuBar; }

    /**
     * Sets the content pane -- the container that holds the components
     * parented by the root pane.
     * <p>
     * Swing's painting architecture requires an opaque <code>JComponent</code>
     * in the containment hierarchy. This is typically provided by the
     * content pane. If you replace the content pane it is recommended you
     * replace it with an opaque <code>JComponent</code>.
     *
     * @param content the <code>Container</code> to use for component-contents
     * @throws java.awt.IllegalComponentStateException (a runtime
     *            exception) if the content pane parameter is <code>null</code>
     */
    public void setContentPane(Container content) {
        if(content == null)
            throw new IllegalComponentStateException("contentPane cannot be set to null.");
        if(contentPane != null && contentPane.getParent() == layeredPane)
            layeredPane.remove(contentPane);
        contentPane = content;

        layeredPane.add(contentPane, JLayeredPane.FRAME_CONTENT_LAYER);
    }

    /**
     * Returns the content pane -- the container that holds the components
     * parented by the root pane.
     *
     * @return the <code>Container</code> that holds the component-contents
     */
    public Container getContentPane() { return contentPane; }

// PENDING(klobad) Should this reparent the contentPane and MenuBar?
    /**
     * Sets the layered pane for the root pane. The layered pane
     * typically holds a content pane and an optional <code>JMenuBar</code>.
     *
     * @param layered  the <code>JLayeredPane</code> to use
     * @throws java.awt.IllegalComponentStateException (a runtime
     *            exception) if the layered pane parameter is <code>null</code>
     */
    public void setLayeredPane(JLayeredPane layered) {
        if(layered == null)
            throw new IllegalComponentStateException("layeredPane cannot be set to null.");
        if(layeredPane != null && layeredPane.getParent() == this)
            this.remove(layeredPane);
        layeredPane = layered;

        this.add(layeredPane, -1);
    }
    /**
     * Gets the layered pane used by the root pane. The layered pane
     * typically holds a content pane and an optional <code>JMenuBar</code>.
     *
     * @return the <code>JLayeredPane</code> currently in use
     */
    public JLayeredPane getLayeredPane() { return layeredPane; }

    /**
     * Sets a specified <code>Component</code> to be the glass pane for this
     * root pane.  The glass pane should normally be a lightweight,
     * transparent component, because it will be made visible when
     * ever the root pane needs to grab input events.
     * <p>
     * The new glass pane's visibility is changed to match that of
     * the current glass pane.  An implication of this is that care
     * must be taken when you want to replace the glass pane and
     * make it visible.  Either of the following will work:
     * <pre>
     *   root.setGlassPane(newGlassPane);
     *   newGlassPane.setVisible(true);
     * </pre>
     * or:
     * <pre>
     *   root.getGlassPane().setVisible(true);
     *   root.setGlassPane(newGlassPane);
     * </pre>
     *
     * @param glass the <code>Component</code> to use as the glass pane
     *              for this <code>JRootPane</code>
     * @throws NullPointerException if the <code>glass</code> parameter is
     *          <code>null</code>
     */
    public void setGlassPane(Component glass) {
        if (glass == null) {
            throw new NullPointerException("glassPane cannot be set to null.");
        }

        glass.setMixingCutoutShape(new Rectangle());

        boolean visible = false;
        if (glassPane != null && glassPane.getParent() == this) {
            this.remove(glassPane);
            visible = glassPane.isVisible();
        }

        glass.setVisible(visible);
        glassPane = glass;
        this.add(glassPane, 0);
        if (visible) {
            repaint();
        }
    }

    /**
     * Returns the current glass pane for this <code>JRootPane</code>.
     * @return the current glass pane
     * @see #setGlassPane
     */
    public Component getGlassPane() {
        return glassPane;
    }

    /**
     * If a descendant of this <code>JRootPane</code> calls
     * <code>revalidate</code>, validate from here on down.
     *<p>
     * Deferred requests to layout a component and its descendents again.
     * For example, calls to <code>revalidate</code>, are pushed upwards to
     * either a <code>JRootPane</code> or a <code>JScrollPane</code>
     * because both classes override <code>isValidateRoot</code> to return true.
     *
     * @see JComponent#isValidateRoot
     * @see java.awt.Container#isValidateRoot
     * @return true
     */
    @Override
    public boolean isValidateRoot() {
        return true;
    }

    /**
     * The <code>glassPane</code> and <code>contentPane</code>
     * have the same bounds, which means <code>JRootPane</code>
     * does not tiles its children and this should return false.
     * On the other hand, the <code>glassPane</code>
     * is normally not visible, and so this can return true if the
     * <code>glassPane</code> isn't visible. Therefore, the
     * return value here depends upon the visibility of the
     * <code>glassPane</code>.
     *
     * @return true if this component's children don't overlap
     */
    public boolean isOptimizedDrawingEnabled() {
        return !glassPane.isVisible();
    }

    /**
     * {@inheritDoc}
     */
    public void addNotify() {
        super.addNotify();
        enableEvents(AWTEvent.KEY_EVENT_MASK);
    }

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


    /**
     * Sets the <code>defaultButton</code> property,
     * which determines the current default button for this <code>JRootPane</code>.
     * The default button is the button which will be activated
     * when a UI-defined activation event (typically the <b>Enter</b> key)
     * occurs in the root pane regardless of whether or not the button
     * has keyboard focus (unless there is another component within
     * the root pane which consumes the activation event,
     * such as a <code>JTextPane</code>).
     * For default activation to work, the button must be an enabled
     * descendent of the root pane when activation occurs.
     * To remove a default button from this root pane, set this
     * property to <code>null</code>.
     *
     * @see JButton#isDefaultButton
     * @param defaultButton the <code>JButton</code> which is to be the default button
     */
    @BeanProperty(description
            = "The button activated by default in this root pane")
    public void setDefaultButton(JButton defaultButton) {
        JButton oldDefault = this.defaultButton;

        if (oldDefault != defaultButton) {
            this.defaultButton = defaultButton;

            if (oldDefault != null) {
                oldDefault.repaint();
            }
            if (defaultButton != null) {
                defaultButton.repaint();
            }
        }

        firePropertyChange("defaultButton", oldDefault, defaultButton);
    }

    /**
     * Returns the value of the <code>defaultButton</code> property.
     * @return the <code>JButton</code> which is currently the default button
     * @see #setDefaultButton
     */
    public JButton getDefaultButton() {
        return defaultButton;
    }

    final void setUseTrueDoubleBuffering(boolean useTrueDoubleBuffering) {
        this.useTrueDoubleBuffering = useTrueDoubleBuffering;
    }

    final boolean getUseTrueDoubleBuffering() {
        return useTrueDoubleBuffering;
    }

    final void disableTrueDoubleBuffering() {
        if (useTrueDoubleBuffering) {
            if (!IGNORE_DISABLE_TRUE_DOUBLE_BUFFERING) {
                if (LOG_DISABLE_TRUE_DOUBLE_BUFFERING) {
                    System.out.println("Disabling true double buffering for " +
                                       this);
                    Thread.dumpStack();
                }
                useTrueDoubleBuffering = false;
                RepaintManager.currentManager(this).
                        doubleBufferingChanged(this);
            }
        }
    }

    /**
     * Overridden to enforce the position of the glass component as
     * the zero child.
     *
     * @param comp the component to be enhanced
     * @param constraints the constraints to be respected
     * @param index the index
     */
    protected void addImpl(Component comp, Object constraints, int index) {
        super.addImpl(comp, constraints, index);

        /// We are making sure the glassPane is on top.
        if(glassPane != null
            && glassPane.getParent() == this
            && getComponent(0) != glassPane) {
            add(glassPane, 0);
        }
    }


///////////////////////////////////////////////////////////////////////////////
//// Begin Inner Classes
///////////////////////////////////////////////////////////////////////////////


    /**
     * A custom layout manager that is responsible for the layout of
     * layeredPane, glassPane, and menuBar.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    @SuppressWarnings("serial")
    protected class RootLayout implements LayoutManager2, Serializable
    {
        /**
         * Constructs a {@code RootLayout}.
         */
        protected RootLayout() {}

        /**
         * Returns the amount of space the layout would like to have.
         *
         * @param parent the Container for which this layout manager
         * is being used
         * @return a Dimension object containing the layout's preferred size
         */
        public Dimension preferredLayoutSize(Container parent) {
            Dimension rd, mbd;
            Insets i = getInsets();

            if(contentPane != null) {
                rd = contentPane.getPreferredSize();
            } else {
                rd = parent.getSize();
            }
            if(menuBar != null && menuBar.isVisible()) {
                mbd = menuBar.getPreferredSize();
            } else {
                mbd = new Dimension(0, 0);
            }
            return new Dimension(Math.max(rd.width, mbd.width) + i.left + i.right,
                                        rd.height + mbd.height + i.top + i.bottom);
        }

        /**
         * Returns the minimum amount of space the layout needs.
         *
         * @param parent the Container for which this layout manager
         * is being used
         * @return a Dimension object containing the layout's minimum size
         */
        public Dimension minimumLayoutSize(Container parent) {
            Dimension rd, mbd;
            Insets i = getInsets();
            if(contentPane != null) {
                rd = contentPane.getMinimumSize();
            } else {
                rd = parent.getSize();
            }
            if(menuBar != null && menuBar.isVisible()) {
                mbd = menuBar.getMinimumSize();
            } else {
                mbd = new Dimension(0, 0);
            }
            return new Dimension(Math.max(rd.width, mbd.width) + i.left + i.right,
                        rd.height + mbd.height + i.top + i.bottom);
        }

        /**
         * Returns the maximum amount of space the layout can use.
         *
         * @param target the Container for which this layout manager
         * is being used
         * @return a Dimension object containing the layout's maximum size
         */
        public Dimension maximumLayoutSize(Container target) {
            Dimension rd, mbd;
            Insets i = getInsets();
            if(menuBar != null && menuBar.isVisible()) {
                mbd = menuBar.getMaximumSize();
            } else {
                mbd = new Dimension(0, 0);
            }
            if(contentPane != null) {
                rd = contentPane.getMaximumSize();
            } else {
                // This is silly, but should stop an overflow error
                rd = new Dimension(Integer.MAX_VALUE,
                        Integer.MAX_VALUE - i.top - i.bottom - mbd.height - 1);
            }
            return new Dimension(Math.max(rd.width, mbd.width) + i.left + i.right,
                                         rd.height + mbd.height + i.top + i.bottom);
        }

        /**
         * Instructs the layout manager to perform the layout for the specified
         * container.
         *
         * @param parent the Container for which this layout manager
         * is being used
         */
        public void layoutContainer(Container parent) {
            Rectangle b = parent.getBounds();
            Insets i = getInsets();
            int contentY = 0;
            int w = b.width - i.right - i.left;
            int h = b.height - i.top - i.bottom;

            if(layeredPane != null) {
                layeredPane.setBounds(i.left, i.top, w, h);
            }
            if(glassPane != null) {
                glassPane.setBounds(i.left, i.top, w, h);
            }
            // Note: This is laying out the children in the layeredPane,
            // technically, these are not our children.
            if(menuBar != null && menuBar.isVisible()) {
                Dimension mbd = menuBar.getPreferredSize();
                menuBar.setBounds(0, 0, w, mbd.height);
                contentY += mbd.height;
            }
            if(contentPane != null) {
                contentPane.setBounds(0, contentY, w, h - contentY);
            }
        }

        public void addLayoutComponent(String name, Component comp) {}
        public void removeLayoutComponent(Component comp) {}
        public void addLayoutComponent(Component comp, Object constraints) {}
        public float getLayoutAlignmentX(Container target) { return 0.0f; }
        public float getLayoutAlignmentY(Container target) { return 0.0f; }
        public void invalidateLayout(Container target) {}
    }

    /**
     * Returns a string representation of this <code>JRootPane</code>.
     * This method is intended to be used only for debugging purposes,
     * and the content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not
     * be <code>null</code>.
     *
     * @return  a string representation of this <code>JRootPane</code>.
     */
    protected String paramString() {
        return super.paramString();
    }

/////////////////
// Accessibility support
////////////////

    /**
     * Gets the <code>AccessibleContext</code> associated with this
     * <code>JRootPane</code>. For root panes, the
     * <code>AccessibleContext</code> takes the form of an
     * <code>AccessibleJRootPane</code>.
     * A new <code>AccessibleJRootPane</code> instance is created if necessary.
     *
     * @return an <code>AccessibleJRootPane</code> that serves as the
     *         <code>AccessibleContext</code> of this <code>JRootPane</code>
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJRootPane();
        }
        return accessibleContext;
    }

    /**
     * This class implements accessibility support for the
     * <code>JRootPane</code> class.  It provides an implementation of the
     * Java Accessibility API appropriate to root pane user-interface elements.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    @SuppressWarnings("serial")
    protected class AccessibleJRootPane extends AccessibleJComponent {

        /**
         * Constructs an {@code AccessibleJRootPane}.
         */
        protected AccessibleJRootPane() {}

        /**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of
         * the object
         */
        public AccessibleRole getAccessibleRole() {
            return AccessibleRole.ROOT_PANE;
        }

        /**
         * Returns the number of accessible children of the object.
         *
         * @return the number of accessible children of the object.
         */
        public int getAccessibleChildrenCount() {
            return super.getAccessibleChildrenCount();
        }

        /**
         * Returns the specified Accessible child of the object.  The Accessible
         * children of an Accessible object are zero-based, so the first child
         * of an Accessible child is at index 0, the second child is at index 1,
         * and so on.
         *
         * @param i zero-based index of child
         * @return the Accessible child of the object
         * @see #getAccessibleChildrenCount
         */
        public Accessible getAccessibleChild(int i) {
            return super.getAccessibleChild(i);
        }
    } // inner class AccessibleJRootPane
}