gt:             if (!IGNORE_DISABLE_TRUE_DOUBLE_BUFFERING) {
context: /*
   * Copyright (c) 1997, 2007, 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.applet.Applet;
  import java.awt.*;
  import java.awt.event.*;
  import java.beans.*;
  import java.security.AccessController;
  import javax.accessibility.*;
  import javax.swing.plaf.RootPaneUI;
  import java.util.Vector;
  import java.io.Serializable;
  import javax.swing.border.*;
  import sun.awt.AWTAccessor;
  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="http://java.sun.com/docs/books/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 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>
   * <table align="right" border="0" summary="layout">
   * <tr>
   * <td align="center">
   * <img src="doc-files/JRootPane-2.gif"
   * alt="The following text describes this graphic." HEIGHT=386 WIDTH=349>
   * </td>
   * </tr>
   * </table>
   * 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 hieararchy 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<sup><font size="-2">TM</font></sup>
   * 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://java.sun.com/products/jfc/tsc/articles/mixing/">
   * Mixing Heavy and Light Components</a>
   *
   * @author David Kloba
   */
  /// 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.
       */
      private static final boolean LOG_DISABLE_TRUE_DOUBLE_BUFFERING;
  
      /**
       * Whether or not we should ignore requests to disable true double
       * buffering. Default is false.
       */
      private static final boolean IGNORE_DISABLE_TRUE_DOUBLE_BUFFERING;
  
      /**
       * 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;
      /**
       * As of Java 2 platform v1.3 this unusable field is no longer used.
       * To override the default button you should replace the <code>Action</code>
       * in the <code>JRootPane</code>'s <code>ActionMap</code>. Please refer to
       * the key bindings specification for further details.
       *
       * @deprecated As of Java 2 platform v1.3.
       *  @see #defaultButton
       */
      @Deprecated
      protected DefaultAction defaultPressAction;
      /**
       * As of Java 2 platform v1.3 this unusable field is no longer used.
       * To override the default button you should replace the <code>Action</code>
       * in the <code>JRootPane</code>'s <code>ActionMap</code>. Please refer to
       * the key bindings specification for further details.
       *
       * @deprecated As of Java 2 platform v1.3.
       *  @see #defaultButton
       */
      @Deprecated
      protected DefaultAction defaultReleaseAction;
  
      /**
       * 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;
  
      static {
          LOG_DISABLE_TRUE_DOUBLE_BUFFERING =
              AccessController.doPrivileged(new GetBooleanAction(
                                     "swing.logDoubleBufferingDisable"));
          IGNORE_DISABLE_TRUE_DOUBLE_BUFFERING =
              AccessController.doPrivileged(new GetBooleanAction(
                                     "swing.ignoreDoubleBufferingDisable"));
      }
  
      /**
       * 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
       * @beaninfo
       *        bound: true
       *         enum: NONE                   JRootPane.NONE
       *               FRAME                  JRootPane.FRAME
       *               PLAIN_DIALOG           JRootPane.PLAIN_DIALOG
       *               INFORMATION_DIALOG     JRootPane.INFORMATION_DIALOG
       *               ERROR_DIALOG           JRootPane.ERROR_DIALOG
       *               COLOR_CHOOSER_DIALOG   JRootPane.COLOR_CHOOSER_DIALOG
       *               FILE_CHOOSER_DIALOG    JRootPane.FILE_CHOOSER_DIALOG
       *               QUESTION_DIALOG        JRootPane.QUESTION_DIALOG
       *               WARNING_DIALOG         JRootPane.WARNING_DIALOG
       *       expert: true
       *    attribute: visualUpdate true
       *  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&F object that renders this component.
       *
       * @return <code>LabelUI</code> object
       * @since 1.3
       */
      public RootPaneUI getUI() {
          return (RootPaneUI)ui;
      }
  
      /**
       * Sets the L&F object that renders this component.
       *
       * @param ui  the <code>LabelUI</code> L&F object
       * @see UIDefaults#getUI
       * @beaninfo
       *        bound: true
       *       hidden: true
       *      expert: true
       *    attribute: visualUpdate true
       *  description: The UI object that implements the Component's LookAndFeel.
       * @since 1.3
       */
      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&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() {
          JComponent c = new JPanel();
          c.setName(this.getName()+".glassPane");
          c.setVisible(false);
          ((JPanel)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)
              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 hiearchy. 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
       * @exception 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
       * @exception 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>
       * @exception 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.");
          }
  
          AWTAccessor.getComponentAccessor().setMixingCutoutShape(glass,
                  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 visiblity 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
       *
       * @beaninfo
       *  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) {
  