/*
 * Copyright (c) 2000, 2018, 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
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 * questions.
 */
package java.awt;

import java.awt.event.FocusEvent;
import java.awt.event.KeyEvent;
import java.awt.event.WindowEvent;
import java.awt.peer.ComponentPeer;
import java.awt.peer.LightweightPeer;
import java.lang.ref.WeakReference;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.Set;

import sun.awt.AWTAccessor;
import sun.awt.AppContext;
import sun.awt.SunToolkit;
import sun.awt.TimedWindowEvent;
import sun.util.logging.PlatformLogger;

The default KeyboardFocusManager for AWT applications. Focus traversal is
done in response to a Component's focus traversal keys, and using a
Container's FocusTraversalPolicy.

Please see

How to Use the Focus Subsystem,
a section in The Java Tutorial, and the
Focus Specification
for more information.
Author:
David Mendenhall
See Also:
FocusTraversalPolicy
Component.setFocusTraversalKeys
Component.getFocusTraversalKeys
Since:
1.4/**
 * The default KeyboardFocusManager for AWT applications. Focus traversal is
 * done in response to a Component's focus traversal keys, and using a
 * Container's FocusTraversalPolicy.
 * <p>
 * Please see
 * <a href="https://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html">
 * How to Use the Focus Subsystem</a>,
 * a section in <em>The Java Tutorial</em>, and the
 * <a href="../../java/awt/doc-files/FocusSpec.html">Focus Specification</a>
 * for more information.
 *
 * @author David Mendenhall
 *
 * @see FocusTraversalPolicy
 * @see Component#setFocusTraversalKeys
 * @see Component#getFocusTraversalKeys
 * @since 1.4
 */
public class DefaultKeyboardFocusManager extends KeyboardFocusManager {
    private static final PlatformLogger focusLog = PlatformLogger.getLogger("java.awt.focus.DefaultKeyboardFocusManager");

    // null weak references to not create too many objects
    private static final WeakReference<Window> NULL_WINDOW_WR =
        new WeakReference<Window>(null);
    private static final WeakReference<Component> NULL_COMPONENT_WR =
        new WeakReference<Component>(null);
    private WeakReference<Window> realOppositeWindowWR = NULL_WINDOW_WR;
    private WeakReference<Component> realOppositeComponentWR = NULL_COMPONENT_WR;
    private int inSendMessage;
    private LinkedList<KeyEvent> enqueuedKeyEvents = new LinkedList<KeyEvent>();
    private LinkedList<TypeAheadMarker> typeAheadMarkers = new LinkedList<TypeAheadMarker>();
    private boolean consumeNextKeyTyped;
    private Component restoreFocusTo;

    private static boolean fxAppThreadIsDispatchThread;

    static {
        AWTAccessor.setDefaultKeyboardFocusManagerAccessor(
            new AWTAccessor.DefaultKeyboardFocusManagerAccessor() {
                public void consumeNextKeyTyped(DefaultKeyboardFocusManager dkfm, KeyEvent e) {
                    dkfm.consumeNextKeyTyped(e);
                }
            });
        AccessController.doPrivileged(new PrivilegedAction<Object>() {
            public Object run() {
                fxAppThreadIsDispatchThread =
                        "true".equals(System.getProperty("javafx.embed.singleThread"));
                return null;
            }
        });
    }

    private static class TypeAheadMarker {
        long after;
        Component untilFocused;

        TypeAheadMarker(long after, Component untilFocused) {
            this.after = after;
            this.untilFocused = untilFocused;
        }
        
Returns string representation of the marker
/**
         * Returns string representation of the marker
         */
        public String toString() {
            return ">>> Marker after " + after + " on " + untilFocused;
        }
    }

    private Window getOwningFrameDialog(Window window) {
        while (window != null && !(window instanceof Frame ||
                                   window instanceof Dialog)) {
            window = (Window)window.getParent();
        }
        return window;
    }

    /*
     * This series of restoreFocus methods is used for recovering from a
     * rejected focus or activation change. Rejections typically occur when
     * the user attempts to focus a non-focusable Component or Window.
     */
    private void restoreFocus(FocusEvent fe, Window newFocusedWindow) {
        Component realOppositeComponent = this.realOppositeComponentWR.get();
        Component vetoedComponent = fe.getComponent();

        if (newFocusedWindow != null && restoreFocus(newFocusedWindow,
                                                     vetoedComponent, false))
        {
        } else if (realOppositeComponent != null &&
                   doRestoreFocus(realOppositeComponent, vetoedComponent, false)) {
        } else if (fe.getOppositeComponent() != null &&
                   doRestoreFocus(fe.getOppositeComponent(), vetoedComponent, false)) {
        } else {
            clearGlobalFocusOwnerPriv();
        }
    }
    private void restoreFocus(WindowEvent we) {
        Window realOppositeWindow = this.realOppositeWindowWR.get();
        if (realOppositeWindow != null
            && restoreFocus(realOppositeWindow, null, false))
        {
            // do nothing, everything is done in restoreFocus()
        } else if (we.getOppositeWindow() != null &&
                   restoreFocus(we.getOppositeWindow(), null, false))
        {
            // do nothing, everything is done in restoreFocus()
        } else {
            clearGlobalFocusOwnerPriv();
        }
    }
    private boolean restoreFocus(Window aWindow, Component vetoedComponent,
                                 boolean clearOnFailure) {
        restoreFocusTo = null;
        Component toFocus =
            KeyboardFocusManager.getMostRecentFocusOwner(aWindow);

        if (toFocus != null && toFocus != vetoedComponent) {
            if (getHeavyweight(aWindow) != getNativeFocusOwner()) {
                // cannot restore focus synchronously
                if (!toFocus.isShowing() || !toFocus.canBeFocusOwner()) {
                    toFocus = toFocus.getNextFocusCandidate();
                }
                if (toFocus != null && toFocus != vetoedComponent) {
                    if (!toFocus.requestFocus(false,
                                                   FocusEvent.Cause.ROLLBACK)) {
                        restoreFocusTo = toFocus;
                    }
                    return true;
                }
            } else if (doRestoreFocus(toFocus, vetoedComponent, false)) {
                return true;
            }
        }
        if (clearOnFailure) {
            clearGlobalFocusOwnerPriv();
            return true;
        } else {
            return false;
        }
    }
    private boolean restoreFocus(Component toFocus, boolean clearOnFailure) {
        return doRestoreFocus(toFocus, null, clearOnFailure);
    }
    private boolean doRestoreFocus(Component toFocus, Component vetoedComponent,
                                   boolean clearOnFailure)
    {
        boolean success = true;
        if (toFocus != vetoedComponent && toFocus.isShowing() && toFocus.canBeFocusOwner() &&
            (success = toFocus.requestFocus(false, FocusEvent.Cause.ROLLBACK)))
        {
            return true;
        } else {
            if (!success && getGlobalFocusedWindow() != SunToolkit.getContainingWindow(toFocus)) {
                restoreFocusTo = toFocus;
                return true;
            }
            Component nextFocus = toFocus.getNextFocusCandidate();
            if (nextFocus != null && nextFocus != vetoedComponent &&
                nextFocus.requestFocusInWindow(FocusEvent.Cause.ROLLBACK))
            {
                return true;
            } else if (clearOnFailure) {
                clearGlobalFocusOwnerPriv();
                return true;
            } else {
                return false;
            }
        }
    }

    
A special type of SentEvent which updates a counter in the target
KeyboardFocusManager if it is an instance of
DefaultKeyboardFocusManager.
/**
     * A special type of SentEvent which updates a counter in the target
     * KeyboardFocusManager if it is an instance of
     * DefaultKeyboardFocusManager.
     */
    private static class DefaultKeyboardFocusManagerSentEvent
        extends SentEvent
    {
        /*
         * serialVersionUID
         */
        private static final long serialVersionUID = -2924743257508701758L;

        public DefaultKeyboardFocusManagerSentEvent(AWTEvent nested,
                                                    AppContext toNotify) {
            super(nested, toNotify);
        }
        public final void dispatch() {
            KeyboardFocusManager manager =
                KeyboardFocusManager.getCurrentKeyboardFocusManager();
            DefaultKeyboardFocusManager defaultManager =
                (manager instanceof DefaultKeyboardFocusManager)
                ? (DefaultKeyboardFocusManager)manager
                : null;

            if (defaultManager != null) {
                synchronized (defaultManager) {
                    defaultManager.inSendMessage++;
                }
            }

            super.dispatch();

            if (defaultManager != null) {
                synchronized (defaultManager) {
                    defaultManager.inSendMessage--;
                }
            }
        }
    }

    
Sends a synthetic AWTEvent to a Component. If the Component is in
the current AppContext, then the event is immediately dispatched.
If the Component is in a different AppContext, then the event is
posted to the other AppContext's EventQueue, and this method blocks
until the event is handled or target AppContext is disposed.
Returns true if successfully dispatched event, false if failed
to dispatch.
/**
     * Sends a synthetic AWTEvent to a Component. If the Component is in
     * the current AppContext, then the event is immediately dispatched.
     * If the Component is in a different AppContext, then the event is
     * posted to the other AppContext's EventQueue, and this method blocks
     * until the event is handled or target AppContext is disposed.
     * Returns true if successfully dispatched event, false if failed
     * to dispatch.
     */
    static boolean sendMessage(Component target, AWTEvent e) {
        e.isPosted = true;
        AppContext myAppContext = AppContext.getAppContext();
        final AppContext targetAppContext = target.appContext;
        final SentEvent se =
            new DefaultKeyboardFocusManagerSentEvent(e, myAppContext);

        if (myAppContext == targetAppContext) {
            se.dispatch();
        } else {
            if (targetAppContext.isDisposed()) {
                return false;
            }
            SunToolkit.postEvent(targetAppContext, se);
            if (EventQueue.isDispatchThread()) {
                if (Thread.currentThread() instanceof EventDispatchThread) {
                    EventDispatchThread edt = (EventDispatchThread)
                            Thread.currentThread();
                    edt.pumpEvents(SentEvent.ID, new Conditional() {
                        public boolean evaluate() {
                            return !se.dispatched && !targetAppContext.isDisposed();
                        }
                    });
                } else {
                    if (fxAppThreadIsDispatchThread) {
                        Thread fxCheckDispatchThread = new Thread() {
                            @Override
                            public void run() {
                                while (!se.dispatched && !targetAppContext.isDisposed()) {
                                    try {
                                        Thread.sleep(100);
                                    } catch (InterruptedException e) {
                                        break;
                                    }
                                }
                            }
                        };
                        fxCheckDispatchThread.start();
                        try {
                            // check if event is dispatched or disposed
                            // but since this user app thread is same as
                            // dispatch thread in fx when run with
                            // javafx.embed.singleThread=true
                            // we do not wait infinitely to avoid deadlock
                            // as dispatch will ultimately be done by this thread
                            fxCheckDispatchThread.join(500);
                        } catch (InterruptedException ex) {
                        }
                    }
                }
            } else {
                synchronized (se) {
                    while (!se.dispatched && !targetAppContext.isDisposed()) {
                        try {
                            se.wait(1000);
                        } catch (InterruptedException ie) {
                            break;
                        }
                    }
                }
            }
        }
        return se.dispatched;
    }

    /*
     * Checks if the focus window event follows key events waiting in the type-ahead
     * queue (if any). This may happen when a user types ahead in the window, the client
     * listeners hang EDT for a while, and the user switches b/w toplevels. In that
     * case the focus window events may be dispatched before the type-ahead events
     * get handled. This may lead to wrong focus behavior and in order to avoid it,
     * the focus window events are reposted to the end of the event queue. See 6981400.
     */
    private boolean repostIfFollowsKeyEvents(WindowEvent e) {
        if (!(e instanceof TimedWindowEvent)) {
            return false;
        }
        TimedWindowEvent we = (TimedWindowEvent)e;
        long time = we.getWhen();
        synchronized (this) {
            KeyEvent ke = enqueuedKeyEvents.isEmpty() ? null : enqueuedKeyEvents.getFirst();
            if (ke != null && time >= ke.getWhen()) {
                TypeAheadMarker marker = typeAheadMarkers.isEmpty() ? null : typeAheadMarkers.getFirst();
                if (marker != null) {
                    Window toplevel = marker.untilFocused.getContainingWindow();
                    // Check that the component awaiting focus belongs to
                    // the current focused window. See 8015454.
                    if (toplevel != null && toplevel.isFocused()) {
                        SunToolkit.postEvent(AppContext.getAppContext(), new SequencedEvent(e));
                        return true;
                    }
                }
            }
        }
        return false;
    }

    
This method is called by the AWT event dispatcher requesting that the current KeyboardFocusManager dispatch the specified event on its behalf. DefaultKeyboardFocusManagers dispatch all FocusEvents, all WindowEvents related to focus, and all KeyEvents. These events are dispatched based on the KeyboardFocusManager's notion of the focus owner and the focused and active Windows, sometimes overriding the source of the specified AWTEvent. If this method returns false, then the AWT event dispatcher will attempt to dispatch the event itself. 
Params:
e – the AWTEvent to be dispatched
Returns:
true if this method dispatched the event; false otherwise/**
     * This method is called by the AWT event dispatcher requesting that the
     * current KeyboardFocusManager dispatch the specified event on its behalf.
     * DefaultKeyboardFocusManagers dispatch all FocusEvents, all WindowEvents
     * related to focus, and all KeyEvents. These events are dispatched based
     * on the KeyboardFocusManager's notion of the focus owner and the focused
     * and active Windows, sometimes overriding the source of the specified
     * AWTEvent. If this method returns {@code false}, then the AWT event
     * dispatcher will attempt to dispatch the event itself.
     *
     * @param e the AWTEvent to be dispatched
     * @return {@code true} if this method dispatched the event;
     *         {@code false} otherwise
     */
    public boolean dispatchEvent(AWTEvent e) {
        if (focusLog.isLoggable(PlatformLogger.Level.FINE) && (e instanceof WindowEvent || e instanceof FocusEvent)) {
            focusLog.fine("" + e);
        }
        switch (e.getID()) {
            case WindowEvent.WINDOW_GAINED_FOCUS: {
                if (repostIfFollowsKeyEvents((WindowEvent)e)) {
                    break;
                }

                WindowEvent we = (WindowEvent)e;
                Window oldFocusedWindow = getGlobalFocusedWindow();
                Window newFocusedWindow = we.getWindow();
                if (newFocusedWindow == oldFocusedWindow) {
                    break;
                }

                if (!(newFocusedWindow.isFocusableWindow()
                      && newFocusedWindow.isVisible()
                      && newFocusedWindow.isDisplayable()))
                {
                    // we can not accept focus on such window, so reject it.
                    restoreFocus(we);
                    break;
                }
                // If there exists a current focused window, then notify it
                // that it has lost focus.
                if (oldFocusedWindow != null) {
                    boolean isEventDispatched =
                        sendMessage(oldFocusedWindow,
                                new WindowEvent(oldFocusedWindow,
                                                WindowEvent.WINDOW_LOST_FOCUS,
                                                newFocusedWindow));
                    // Failed to dispatch, clear by ourselves
                    if (!isEventDispatched) {
                        setGlobalFocusOwner(null);
                        setGlobalFocusedWindow(null);
                    }
                }

                // Because the native libraries do not post WINDOW_ACTIVATED
                // events, we need to synthesize one if the active Window
                // changed.
                Window newActiveWindow =
                    getOwningFrameDialog(newFocusedWindow);
                Window currentActiveWindow = getGlobalActiveWindow();
                if (newActiveWindow != currentActiveWindow) {
                    sendMessage(newActiveWindow,
                                new WindowEvent(newActiveWindow,
                                                WindowEvent.WINDOW_ACTIVATED,
                                                currentActiveWindow));
                    if (newActiveWindow != getGlobalActiveWindow()) {
                        // Activation change was rejected. Unlikely, but
                        // possible.
                        restoreFocus(we);
                        break;
                    }
                }

                setGlobalFocusedWindow(newFocusedWindow);

                if (newFocusedWindow != getGlobalFocusedWindow()) {
                    // Focus change was rejected. Will happen if
                    // newFocusedWindow is not a focusable Window.
                    restoreFocus(we);
                    break;
                }

                // Restore focus to the Component which last held it. We do
                // this here so that client code can override our choice in
                // a WINDOW_GAINED_FOCUS handler.
                //
                // Make sure that the focus change request doesn't change the
                // focused Window in case we are no longer the focused Window
                // when the request is handled.
                if (inSendMessage == 0) {
                    // Identify which Component should initially gain focus
                    // in the Window.
                    //
                    // * If we're in SendMessage, then this is a synthetic
                    //   WINDOW_GAINED_FOCUS message which was generated by a
                    //   the FOCUS_GAINED handler. Allow the Component to
                    //   which the FOCUS_GAINED message was targeted to
                    //   receive the focus.
                    // * Otherwise, look up the correct Component here.
                    //   We don't use Window.getMostRecentFocusOwner because
                    //   window is focused now and 'null' will be returned


                    // Calculating of most recent focus owner and focus
                    // request should be synchronized on KeyboardFocusManager.class
                    // to prevent from thread race when user will request
                    // focus between calculation and our request.
                    // But if focus transfer is synchronous, this synchronization
                    // may cause deadlock, thus we don't synchronize this block.
                    Component toFocus = KeyboardFocusManager.
                        getMostRecentFocusOwner(newFocusedWindow);
                    boolean isFocusRestore = restoreFocusTo != null &&
                                                      toFocus == restoreFocusTo;
                    if ((toFocus == null) &&
                        newFocusedWindow.isFocusableWindow())
                    {
                        toFocus = newFocusedWindow.getFocusTraversalPolicy().
                            getInitialComponent(newFocusedWindow);
                    }
                    Component tempLost = null;
                    synchronized(KeyboardFocusManager.class) {
                        tempLost = newFocusedWindow.setTemporaryLostComponent(null);
                    }

                    // The component which last has the focus when this window was focused
                    // should receive focus first
                    if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
                        focusLog.finer("tempLost {0}, toFocus {1}",
                                       tempLost, toFocus);
                    }
                    if (tempLost != null) {
                        tempLost.requestFocusInWindow(
                                    isFocusRestore && tempLost == toFocus ?
                                                FocusEvent.Cause.ROLLBACK :
                                                FocusEvent.Cause.ACTIVATION);
                    }

                    if (toFocus != null && toFocus != tempLost) {
                        // If there is a component which requested focus when this window
                        // was inactive it expects to receive focus after activation.
                        toFocus.requestFocusInWindow(FocusEvent.Cause.ACTIVATION);
                    }
                }
                restoreFocusTo = null;

                Window realOppositeWindow = this.realOppositeWindowWR.get();
                if (realOppositeWindow != we.getOppositeWindow()) {
                    we = new WindowEvent(newFocusedWindow,
                                         WindowEvent.WINDOW_GAINED_FOCUS,
                                         realOppositeWindow);
                }
                return typeAheadAssertions(newFocusedWindow, we);
            }

            case WindowEvent.WINDOW_ACTIVATED: {
                WindowEvent we = (WindowEvent)e;
                Window oldActiveWindow = getGlobalActiveWindow();
                Window newActiveWindow = we.getWindow();
                if (oldActiveWindow == newActiveWindow) {
                    break;
                }

                // If there exists a current active window, then notify it that
                // it has lost activation.
                if (oldActiveWindow != null) {
                    boolean isEventDispatched =
                        sendMessage(oldActiveWindow,
                                new WindowEvent(oldActiveWindow,
                                                WindowEvent.WINDOW_DEACTIVATED,
                                                newActiveWindow));
                    // Failed to dispatch, clear by ourselves
                    if (!isEventDispatched) {
                        setGlobalActiveWindow(null);
                    }
                    if (getGlobalActiveWindow() != null) {
                        // Activation change was rejected. Unlikely, but
                        // possible.
                        break;
                    }
                }

                setGlobalActiveWindow(newActiveWindow);

                if (newActiveWindow != getGlobalActiveWindow()) {
                    // Activation change was rejected. Unlikely, but
                    // possible.
                    break;
                }

                return typeAheadAssertions(newActiveWindow, we);
            }

            case FocusEvent.FOCUS_GAINED: {
                restoreFocusTo = null;
                FocusEvent fe = (FocusEvent)e;
                Component oldFocusOwner = getGlobalFocusOwner();
                Component newFocusOwner = fe.getComponent();
                if (oldFocusOwner == newFocusOwner) {
                    if (focusLog.isLoggable(PlatformLogger.Level.FINE)) {
                        focusLog.fine("Skipping {0} because focus owner is the same", e);
                    }
                    // We can't just drop the event - there could be
                    // type-ahead markers associated with it.
                    dequeueKeyEvents(-1, newFocusOwner);
                    break;
                }

                // If there exists a current focus owner, then notify it that
                // it has lost focus.
                if (oldFocusOwner != null) {
                    boolean isEventDispatched =
                        sendMessage(oldFocusOwner,
                                    new FocusEvent(oldFocusOwner,
                                                   FocusEvent.FOCUS_LOST,
                                                   fe.isTemporary(),
                                                   newFocusOwner, fe.getCause()));
                    // Failed to dispatch, clear by ourselves
                    if (!isEventDispatched) {
                        setGlobalFocusOwner(null);
                        if (!fe.isTemporary()) {
                            setGlobalPermanentFocusOwner(null);
                        }
                    }
                }

                // Because the native windowing system has a different notion
                // of the current focus and activation states, it is possible
                // that a Component outside of the focused Window receives a
                // FOCUS_GAINED event. We synthesize a WINDOW_GAINED_FOCUS
                // event in that case.
                final Window newFocusedWindow = SunToolkit.getContainingWindow(newFocusOwner);
                final Window currentFocusedWindow = getGlobalFocusedWindow();
                if (newFocusedWindow != null &&
                    newFocusedWindow != currentFocusedWindow)
                {
                    sendMessage(newFocusedWindow,
                                new WindowEvent(newFocusedWindow,
                                        WindowEvent.WINDOW_GAINED_FOCUS,
                                                currentFocusedWindow));
                    if (newFocusedWindow != getGlobalFocusedWindow()) {
                        // Focus change was rejected. Will happen if
                        // newFocusedWindow is not a focusable Window.

                        // Need to recover type-ahead, but don't bother
                        // restoring focus. That was done by the
                        // WINDOW_GAINED_FOCUS handler
                        dequeueKeyEvents(-1, newFocusOwner);
                        break;
                    }
                }

                if (!(newFocusOwner.isFocusable() && newFocusOwner.isShowing() &&
                    // Refuse focus on a disabled component if the focus event
                    // isn't of UNKNOWN reason (i.e. not a result of a direct request
                    // but traversal, activation or system generated).
                    (newFocusOwner.isEnabled() || fe.getCause().equals(FocusEvent.Cause.UNKNOWN))))
                {
                    // we should not accept focus on such component, so reject it.
                    dequeueKeyEvents(-1, newFocusOwner);
                    if (KeyboardFocusManager.isAutoFocusTransferEnabled()) {
                        // If FOCUS_GAINED is for a disposed component (however
                        // it shouldn't happen) its toplevel parent is null. In this
                        // case we have to try to restore focus in the current focused
                        // window (for the details: 6607170).
                        if (newFocusedWindow == null) {
                            restoreFocus(fe, currentFocusedWindow);
                        } else {
                            restoreFocus(fe, newFocusedWindow);
                        }
                        setMostRecentFocusOwner(newFocusedWindow, null); // see: 8013773
                    }
                    break;
                }

                setGlobalFocusOwner(newFocusOwner);

                if (newFocusOwner != getGlobalFocusOwner()) {
                    // Focus change was rejected. Will happen if
                    // newFocusOwner is not focus traversable.
                    dequeueKeyEvents(-1, newFocusOwner);
                    if (KeyboardFocusManager.isAutoFocusTransferEnabled()) {
                        restoreFocus(fe, newFocusedWindow);
                    }
                    break;
                }

                if (!fe.isTemporary()) {
                    setGlobalPermanentFocusOwner(newFocusOwner);

                    if (newFocusOwner != getGlobalPermanentFocusOwner()) {
                        // Focus change was rejected. Unlikely, but possible.
                        dequeueKeyEvents(-1, newFocusOwner);
                        if (KeyboardFocusManager.isAutoFocusTransferEnabled()) {
                            restoreFocus(fe, newFocusedWindow);
                        }
                        break;
                    }
                }

                setNativeFocusOwner(getHeavyweight(newFocusOwner));

                Component realOppositeComponent = this.realOppositeComponentWR.get();
                if (realOppositeComponent != null &&
                    realOppositeComponent != fe.getOppositeComponent()) {
                    fe = new FocusEvent(newFocusOwner,
                                        FocusEvent.FOCUS_GAINED,
                                        fe.isTemporary(),
                                        realOppositeComponent, fe.getCause());
                    ((AWTEvent) fe).isPosted = true;
                }
                return typeAheadAssertions(newFocusOwner, fe);
            }

            case FocusEvent.FOCUS_LOST: {
                FocusEvent fe = (FocusEvent)e;
                Component currentFocusOwner = getGlobalFocusOwner();
                if (currentFocusOwner == null) {
                    if (focusLog.isLoggable(PlatformLogger.Level.FINE))
                        focusLog.fine("Skipping {0} because focus owner is null", e);
                    break;
                }
                // Ignore cases where a Component loses focus to itself.
                // If we make a mistake because of retargeting, then the
                // FOCUS_GAINED handler will correct it.
                if (currentFocusOwner == fe.getOppositeComponent()) {
                    if (focusLog.isLoggable(PlatformLogger.Level.FINE))
                        focusLog.fine("Skipping {0} because current focus owner is equal to opposite", e);
                    break;
                }

                setGlobalFocusOwner(null);

                if (getGlobalFocusOwner() != null) {
                    // Focus change was rejected. Unlikely, but possible.
                    restoreFocus(currentFocusOwner, true);
                    break;
                }

                if (!fe.isTemporary()) {
                    setGlobalPermanentFocusOwner(null);

                    if (getGlobalPermanentFocusOwner() != null) {
                        // Focus change was rejected. Unlikely, but possible.
                        restoreFocus(currentFocusOwner, true);
                        break;
                    }
                } else {
                    Window owningWindow = currentFocusOwner.getContainingWindow();
                    if (owningWindow != null) {
                        owningWindow.setTemporaryLostComponent(currentFocusOwner);
                    }
                }

                setNativeFocusOwner(null);

                fe.setSource(currentFocusOwner);

                realOppositeComponentWR = (fe.getOppositeComponent() != null)
                    ? new WeakReference<Component>(currentFocusOwner)
                    : NULL_COMPONENT_WR;

                return typeAheadAssertions(currentFocusOwner, fe);
            }

            case WindowEvent.WINDOW_DEACTIVATED: {
                WindowEvent we = (WindowEvent)e;
                Window currentActiveWindow = getGlobalActiveWindow();
                if (currentActiveWindow == null) {
                    break;
                }

                if (currentActiveWindow != e.getSource()) {
                    // The event is lost in time.
                    // Allow listeners to precess the event but do not
                    // change any global states
                    break;
                }

                setGlobalActiveWindow(null);
                if (getGlobalActiveWindow() != null) {
                    // Activation change was rejected. Unlikely, but possible.
                    break;
                }

                we.setSource(currentActiveWindow);
                return typeAheadAssertions(currentActiveWindow, we);
            }

            case WindowEvent.WINDOW_LOST_FOCUS: {
                if (repostIfFollowsKeyEvents((WindowEvent)e)) {
                    break;
                }

                WindowEvent we = (WindowEvent)e;
                Window currentFocusedWindow = getGlobalFocusedWindow();
                Window losingFocusWindow = we.getWindow();
                Window activeWindow = getGlobalActiveWindow();
                Window oppositeWindow = we.getOppositeWindow();
                if (focusLog.isLoggable(PlatformLogger.Level.FINE))
                    focusLog.fine("Active {0}, Current focused {1}, losing focus {2} opposite {3}",
                                  activeWindow, currentFocusedWindow,
                                  losingFocusWindow, oppositeWindow);
                if (currentFocusedWindow == null) {
                    break;
                }

                // Special case -- if the native windowing system posts an
                // event claiming that the active Window has lost focus to the
                // focused Window, then discard the event. This is an artifact
                // of the native windowing system not knowing which Window is
                // really focused.
                if (inSendMessage == 0 && losingFocusWindow == activeWindow &&
                    oppositeWindow == currentFocusedWindow)
                {
                    break;
                }

                Component currentFocusOwner = getGlobalFocusOwner();
                if (currentFocusOwner != null) {
                    // The focus owner should always receive a FOCUS_LOST event
                    // before the Window is defocused.
                    Component oppositeComp = null;
                    if (oppositeWindow != null) {
                        oppositeComp = oppositeWindow.getTemporaryLostComponent();
                        if (oppositeComp == null) {
                            oppositeComp = oppositeWindow.getMostRecentFocusOwner();
                        }
                    }
                    if (oppositeComp == null) {
                        oppositeComp = oppositeWindow;
                    }
                    sendMessage(currentFocusOwner,
                                new FocusEvent(currentFocusOwner,
                                               FocusEvent.FOCUS_LOST,
                                               true,
                                               oppositeComp, FocusEvent.Cause.ACTIVATION));
                }

                setGlobalFocusedWindow(null);
                if (getGlobalFocusedWindow() != null) {
                    // Focus change was rejected. Unlikely, but possible.
                    restoreFocus(currentFocusedWindow, null, true);
                    break;
                }

                we.setSource(currentFocusedWindow);
                realOppositeWindowWR = (oppositeWindow != null)
                    ? new WeakReference<Window>(currentFocusedWindow)
                    : NULL_WINDOW_WR;
                typeAheadAssertions(currentFocusedWindow, we);

                if (oppositeWindow == null && activeWindow != null) {
                    // Then we need to deactivate the active Window as well.
                    // No need to synthesize in other cases, because
                    // WINDOW_ACTIVATED will handle it if necessary.
                    sendMessage(activeWindow,
                                new WindowEvent(activeWindow,
                                                WindowEvent.WINDOW_DEACTIVATED,
                                                null));
                    if (getGlobalActiveWindow() != null) {
                        // Activation change was rejected. Unlikely,
                        // but possible.
                        restoreFocus(currentFocusedWindow, null, true);
                    }
                }
                break;
            }

            case KeyEvent.KEY_TYPED:
            case KeyEvent.KEY_PRESSED:
            case KeyEvent.KEY_RELEASED:
                return typeAheadAssertions(null, e);

            default:
                return false;
        }

        return true;
    }

    
Called by dispatchEvent if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered. If the event has not been consumed, its target is enabled, and the focus owner is not null, this method dispatches the event to its target. This method will also subsequently dispatch the event to all registered KeyEventPostProcessors. After all this operations are finished, the event is passed to peers for processing. 
 In all cases, this method returns true, since DefaultKeyboardFocusManager is designed so that neither dispatchEvent, nor the AWT event dispatcher, should take further action on the event in any situation. 
Params:
e – the KeyEvent to be dispatched
See Also:
Component.dispatchEvent
Returns:
true/**
     * Called by {@code dispatchEvent} if no other
     * KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or
     * if no other KeyEventDispatchers are registered. If the event has not
     * been consumed, its target is enabled, and the focus owner is not null,
     * this method dispatches the event to its target. This method will also
     * subsequently dispatch the event to all registered
     * KeyEventPostProcessors. After all this operations are finished,
     * the event is passed to peers for processing.
     * <p>
     * In all cases, this method returns {@code true}, since
     * DefaultKeyboardFocusManager is designed so that neither
     * {@code dispatchEvent}, nor the AWT event dispatcher, should take
     * further action on the event in any situation.
     *
     * @param e the KeyEvent to be dispatched
     * @return {@code true}
     * @see Component#dispatchEvent
     */
    public boolean dispatchKeyEvent(KeyEvent e) {
        Component focusOwner = (((AWTEvent)e).isPosted) ? getFocusOwner() : e.getComponent();

        if (focusOwner != null && focusOwner.isShowing() && focusOwner.canBeFocusOwner()) {
            if (!e.isConsumed()) {
                Component comp = e.getComponent();
                if (comp != null && comp.isEnabled()) {
                    redispatchEvent(comp, e);
                }
            }
        }
        boolean stopPostProcessing = false;
        java.util.List<KeyEventPostProcessor> processors = getKeyEventPostProcessors();
        if (processors != null) {
            for (java.util.Iterator<KeyEventPostProcessor> iter = processors.iterator();
                 !stopPostProcessing && iter.hasNext(); )
            {
                stopPostProcessing = iter.next().
                            postProcessKeyEvent(e);
            }
        }
        if (!stopPostProcessing) {
            postProcessKeyEvent(e);
        }

        // Allow the peer to process KeyEvent
        Component source = e.getComponent();
        ComponentPeer peer = source.peer;

        if (peer == null || peer instanceof LightweightPeer) {
            // if focus owner is lightweight then its native container
            // processes event
            Container target = source.getNativeContainer();
            if (target != null) {
                peer = target.peer;
            }
        }
        if (peer != null) {
            peer.handleEvent(e);
        }

        return true;
    }

    
This method will be called by dispatchKeyEvent. It will handle any unconsumed KeyEvents that map to an AWT MenuShortcut by consuming the event and activating the shortcut. 
Params:
e – the KeyEvent to post-process
See Also:
dispatchKeyEvent
MenuShortcut
Returns:
true/**
     * This method will be called by {@code dispatchKeyEvent}. It will
     * handle any unconsumed KeyEvents that map to an AWT
     * {@code MenuShortcut} by consuming the event and activating the
     * shortcut.
     *
     * @param e the KeyEvent to post-process
     * @return {@code true}
     * @see #dispatchKeyEvent
     * @see MenuShortcut
     */
    public boolean postProcessKeyEvent(KeyEvent e) {
        if (!e.isConsumed()) {
            Component target = e.getComponent();
            Container p = (Container)
                (target instanceof Container ? target : target.getParent());
            if (p != null) {
                p.postProcessKeyEvent(e);
            }
        }
        return true;
    }

    private void pumpApprovedKeyEvents() {
        KeyEvent ke;
        do {
            ke = null;
            synchronized (this) {
                if (enqueuedKeyEvents.size() != 0) {
                    ke = enqueuedKeyEvents.getFirst();
                    if (typeAheadMarkers.size() != 0) {
                        TypeAheadMarker marker = typeAheadMarkers.getFirst();
                        // Fixed 5064013: may appears that the events have the same time
                        // if (ke.getWhen() >= marker.after) {
                        // The fix is rolled out.

                        if (ke.getWhen() > marker.after) {
                            ke = null;
                        }
                    }
                    if (ke != null) {
                        if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
                            focusLog.finer("Pumping approved event {0}", ke);
                        }
                        enqueuedKeyEvents.removeFirst();
                    }
                }
            }
            if (ke != null) {
                preDispatchKeyEvent(ke);
            }
        } while (ke != null);
    }

    
Dumps the list of type-ahead queue markers to stderr
/**
     * Dumps the list of type-ahead queue markers to stderr
     */
    void dumpMarkers() {
        if (focusLog.isLoggable(PlatformLogger.Level.FINEST)) {
            focusLog.finest(">>> Markers dump, time: {0}", System.currentTimeMillis());
            synchronized (this) {
                if (typeAheadMarkers.size() != 0) {
                    Iterator<TypeAheadMarker> iter = typeAheadMarkers.iterator();
                    while (iter.hasNext()) {
                        TypeAheadMarker marker = iter.next();
                        focusLog.finest("    {0}", marker);
                    }
                }
            }
        }
    }

    private boolean typeAheadAssertions(Component target, AWTEvent e) {

        // Clear any pending events here as well as in the FOCUS_GAINED
        // handler. We need this call here in case a marker was removed in
        // response to a call to dequeueKeyEvents.
        pumpApprovedKeyEvents();

        switch (e.getID()) {
            case KeyEvent.KEY_TYPED:
            case KeyEvent.KEY_PRESSED:
            case KeyEvent.KEY_RELEASED: {
                KeyEvent ke = (KeyEvent)e;
                synchronized (this) {
                    if (e.isPosted && typeAheadMarkers.size() != 0) {
                        TypeAheadMarker marker = typeAheadMarkers.getFirst();
                        // Fixed 5064013: may appears that the events have the same time
                        // if (ke.getWhen() >= marker.after) {
                        // The fix is rolled out.

                        if (ke.getWhen() > marker.after) {
                            if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
                                focusLog.finer("Storing event {0} because of marker {1}", ke, marker);
                            }
                            enqueuedKeyEvents.addLast(ke);
                            return true;
                        }
                    }
                }

                // KeyEvent was posted before focus change request
                return preDispatchKeyEvent(ke);
            }

            case FocusEvent.FOCUS_GAINED:
                if (focusLog.isLoggable(PlatformLogger.Level.FINEST)) {
                    focusLog.finest("Markers before FOCUS_GAINED on {0}", target);
                }
                dumpMarkers();
                // Search the marker list for the first marker tied to
                // the Component which just gained focus. Then remove
                // that marker, any markers which immediately follow
                // and are tied to the same component, and all markers
                // that precede it. This handles the case where
                // multiple focus requests were made for the same
                // Component in a row and when we lost some of the
                // earlier requests. Since FOCUS_GAINED events will
                // not be generated for these additional requests, we
                // need to clear those markers too.
                synchronized (this) {
                    boolean found = false;
                    if (hasMarker(target)) {
                        for (Iterator<TypeAheadMarker> iter = typeAheadMarkers.iterator();
                             iter.hasNext(); )
                        {
                            if (iter.next().untilFocused == target) {
                                found = true;
                            } else if (found) {
                                break;
                            }
                            iter.remove();
                        }
                    } else {
                        // Exception condition - event without marker
                        if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
                            focusLog.finer("Event without marker {0}", e);
                        }
                    }
                }
                focusLog.finest("Markers after FOCUS_GAINED");
                dumpMarkers();

                redispatchEvent(target, e);

                // Now, dispatch any pending KeyEvents which have been
                // released because of the FOCUS_GAINED event so that we don't
                // have to wait for another event to be posted to the queue.
                pumpApprovedKeyEvents();
                return true;

            default:
                redispatchEvent(target, e);
                return true;
        }
    }

    
Returns true if there are some marker associated with component comp in a markers' queue 
Since:
1.5/**
     * Returns true if there are some marker associated with component {@code comp}
     * in a markers' queue
     * @since 1.5
     */
    private boolean hasMarker(Component comp) {
        for (Iterator<TypeAheadMarker> iter = typeAheadMarkers.iterator(); iter.hasNext(); ) {
            if (iter.next().untilFocused == comp) {
                return true;
            }
        }
        return false;
    }

    
Clears markers queue
Since:
1.5/**
     * Clears markers queue
     * @since 1.5
     */
    void clearMarkers() {
        synchronized(this) {
            typeAheadMarkers.clear();
        }
    }

    @SuppressWarnings("deprecation")
    private boolean preDispatchKeyEvent(KeyEvent ke) {
        if (((AWTEvent) ke).isPosted) {
            Component focusOwner = getFocusOwner();
            ke.setSource(((focusOwner != null) ? focusOwner : getFocusedWindow()));
        }
        if (ke.getSource() == null) {
            return true;
        }

        // Explicitly set the key event timestamp here (not in Component.dispatchEventImpl):
        // - A key event is anyway passed to this method which starts its actual dispatching.
        // - If a key event is put to the type ahead queue, its time stamp should not be registered
        //   until its dispatching actually starts (by this method).
        EventQueue.setCurrentEventAndMostRecentTime(ke);

        /**
         * Fix for 4495473.
         * This fix allows to correctly dispatch events when native
         * event proxying mechanism is active.
         * If it is active we should redispatch key events after
         * we detected its correct target.
         */
        if (KeyboardFocusManager.isProxyActive(ke)) {
            Component source = (Component)ke.getSource();
            Container target = source.getNativeContainer();
            if (target != null) {
                ComponentPeer peer = target.peer;
                if (peer != null) {
                    peer.handleEvent(ke);
                    /**
                     * Fix for 4478780 - consume event after it was dispatched by peer.
                     */
                    ke.consume();
                }
            }
            return true;
        }

        java.util.List<KeyEventDispatcher> dispatchers = getKeyEventDispatchers();
        if (dispatchers != null) {
            for (java.util.Iterator<KeyEventDispatcher> iter = dispatchers.iterator();
                 iter.hasNext(); )
             {
                 if (iter.next().
                     dispatchKeyEvent(ke))
                 {
                     return true;
                 }
             }
        }
        return dispatchKeyEvent(ke);
    }

    /*
     * @param e is a KEY_PRESSED event that can be used
     *          to track the next KEY_TYPED related.
     */
    private void consumeNextKeyTyped(KeyEvent e) {
        consumeNextKeyTyped = true;
    }

    private void consumeTraversalKey(KeyEvent e) {
        e.consume();
        consumeNextKeyTyped = (e.getID() == KeyEvent.KEY_PRESSED) &&
                              !e.isActionKey();
    }

    /*
     * return true if event was consumed
     */
    private boolean consumeProcessedKeyEvent(KeyEvent e) {
        if ((e.getID() == KeyEvent.KEY_TYPED) && consumeNextKeyTyped) {
            e.consume();
            consumeNextKeyTyped = false;
            return true;
        }
        return false;
    }

    
This method initiates a focus traversal operation if and only if the
KeyEvent represents a focus traversal key for the specified
focusedComponent. It is expected that focusedComponent is the current
focus owner, although this need not be the case. If it is not,
focus traversal will nevertheless proceed as if focusedComponent
were the focus owner.
Params:
focusedComponent – the Component that is the basis for a focus
       traversal operation if the specified event represents a focus
       traversal key for the Component
e – the event that may represent a focus traversal key/**
     * This method initiates a focus traversal operation if and only if the
     * KeyEvent represents a focus traversal key for the specified
     * focusedComponent. It is expected that focusedComponent is the current
     * focus owner, although this need not be the case. If it is not,
     * focus traversal will nevertheless proceed as if focusedComponent
     * were the focus owner.
     *
     * @param focusedComponent the Component that is the basis for a focus
     *        traversal operation if the specified event represents a focus
     *        traversal key for the Component
     * @param e the event that may represent a focus traversal key
     */
    public void processKeyEvent(Component focusedComponent, KeyEvent e) {
        // consume processed event if needed
        if (consumeProcessedKeyEvent(e)) {
            return;
        }

        // KEY_TYPED events cannot be focus traversal keys
        if (e.getID() == KeyEvent.KEY_TYPED) {
            return;
        }

        if (focusedComponent.getFocusTraversalKeysEnabled() &&
            !e.isConsumed())
        {
            AWTKeyStroke stroke = AWTKeyStroke.getAWTKeyStrokeForEvent(e),
                oppStroke = AWTKeyStroke.getAWTKeyStroke(stroke.getKeyCode(),
                                                 stroke.getModifiers(),
                                                 !stroke.isOnKeyRelease());
            Set<AWTKeyStroke> toTest;
            boolean contains, containsOpp;

            toTest = focusedComponent.getFocusTraversalKeys(
                KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS);
            contains = toTest.contains(stroke);
            containsOpp = toTest.contains(oppStroke);

            if (contains || containsOpp) {
                consumeTraversalKey(e);
                if (contains) {
                    focusNextComponent(focusedComponent);
                }
                return;
            } else if (e.getID() == KeyEvent.KEY_PRESSED) {
                // Fix for 6637607: consumeNextKeyTyped should be reset.
                consumeNextKeyTyped = false;
            }

            toTest = focusedComponent.getFocusTraversalKeys(
                KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS);
            contains = toTest.contains(stroke);
            containsOpp = toTest.contains(oppStroke);

            if (contains || containsOpp) {
                consumeTraversalKey(e);
                if (contains) {
                    focusPreviousComponent(focusedComponent);
                }
                return;
            }

            toTest = focusedComponent.getFocusTraversalKeys(
                KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS);
            contains = toTest.contains(stroke);
            containsOpp = toTest.contains(oppStroke);

            if (contains || containsOpp) {
                consumeTraversalKey(e);
                if (contains) {
                    upFocusCycle(focusedComponent);
                }
                return;
            }

            if (!((focusedComponent instanceof Container) &&
                  ((Container)focusedComponent).isFocusCycleRoot())) {
                return;
            }

            toTest = focusedComponent.getFocusTraversalKeys(
                KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS);
            contains = toTest.contains(stroke);
            containsOpp = toTest.contains(oppStroke);

            if (contains || containsOpp) {
                consumeTraversalKey(e);
                if (contains) {
                    downFocusCycle((Container)focusedComponent);
                }
            }
        }
    }

    
Delays dispatching of KeyEvents until the specified Component becomes the focus owner. KeyEvents with timestamps later than the specified timestamp will be enqueued until the specified Component receives a FOCUS_GAINED event, or the AWT cancels the delay request by invoking dequeueKeyEvents or discardKeyEvents. 
Params:
after – timestamp of current event, or the current, system time if
       the current event has no timestamp, or the AWT cannot determine
       which event is currently being handled
untilFocused – Component which will receive a FOCUS_GAINED event
       before any pending KeyEvents
See Also:
dequeueKeyEvents
discardKeyEvents/**
     * Delays dispatching of KeyEvents until the specified Component becomes
     * the focus owner. KeyEvents with timestamps later than the specified
     * timestamp will be enqueued until the specified Component receives a
     * FOCUS_GAINED event, or the AWT cancels the delay request by invoking
     * {@code dequeueKeyEvents} or {@code discardKeyEvents}.
     *
     * @param after timestamp of current event, or the current, system time if
     *        the current event has no timestamp, or the AWT cannot determine
     *        which event is currently being handled
     * @param untilFocused Component which will receive a FOCUS_GAINED event
     *        before any pending KeyEvents
     * @see #dequeueKeyEvents
     * @see #discardKeyEvents
     */
    protected synchronized void enqueueKeyEvents(long after,
                                                 Component untilFocused) {
        if (untilFocused == null) {
            return;
        }

        if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
            focusLog.finer("Enqueue at {0} for {1}",
                       after, untilFocused);
        }

        int insertionIndex = 0,
            i = typeAheadMarkers.size();
        ListIterator<TypeAheadMarker> iter = typeAheadMarkers.listIterator(i);

        for (; i > 0; i--) {
            TypeAheadMarker marker = iter.previous();
            if (marker.after <= after) {
                insertionIndex = i;
                break;
            }
        }

        typeAheadMarkers.add(insertionIndex,
                             new TypeAheadMarker(after, untilFocused));
    }

    
Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to enqueueKeyEvents with the same timestamp and Component. If the given timestamp is less than zero, the outstanding enqueue request for the given Component with the oldest timestamp (if
any) should be cancelled.
Params:
after – the timestamp specified in the call to enqueueKeyEvents, or any value < 0
untilFocused – the Component specified in the call to enqueueKeyEvents
See Also:
enqueueKeyEvents
discardKeyEvents/**
     * Releases for normal dispatching to the current focus owner all
     * KeyEvents which were enqueued because of a call to
     * {@code enqueueKeyEvents} with the same timestamp and Component.
     * If the given timestamp is less than zero, the outstanding enqueue
     * request for the given Component with the <b>oldest</b> timestamp (if
     * any) should be cancelled.
     *
     * @param after the timestamp specified in the call to
     *        {@code enqueueKeyEvents}, or any value &lt; 0
     * @param untilFocused the Component specified in the call to
     *        {@code enqueueKeyEvents}
     * @see #enqueueKeyEvents
     * @see #discardKeyEvents
     */
    protected synchronized void dequeueKeyEvents(long after,
                                                 Component untilFocused) {
        if (untilFocused == null) {
            return;
        }

        if (focusLog.isLoggable(PlatformLogger.Level.FINER)) {
            focusLog.finer("Dequeue at {0} for {1}",
                       after, untilFocused);
        }

        TypeAheadMarker marker;
        ListIterator<TypeAheadMarker> iter = typeAheadMarkers.listIterator
            ((after >= 0) ? typeAheadMarkers.size() : 0);

        if (after < 0) {
            while (iter.hasNext()) {
                marker = iter.next();
                if (marker.untilFocused == untilFocused)
                {
                    iter.remove();
                    return;
                }
            }
        } else {
            while (iter.hasPrevious()) {
                marker = iter.previous();
                if (marker.untilFocused == untilFocused &&
                    marker.after == after)
                {
                    iter.remove();
                    return;
                }
            }
        }
    }

    
Discards all KeyEvents which were enqueued because of one or more calls to enqueueKeyEvents with the specified Component, or one of its descendants. 
Params:
comp – the Component specified in one or more calls to enqueueKeyEvents, or a parent of such a Component
See Also:
enqueueKeyEvents
dequeueKeyEvents/**
     * Discards all KeyEvents which were enqueued because of one or more calls
     * to {@code enqueueKeyEvents} with the specified Component, or one of
     * its descendants.
     *
     * @param comp the Component specified in one or more calls to
     *        {@code enqueueKeyEvents}, or a parent of such a Component
     * @see #enqueueKeyEvents
     * @see #dequeueKeyEvents
     */
    protected synchronized void discardKeyEvents(Component comp) {
        if (comp == null) {
            return;
        }

        long start = -1;

        for (Iterator<TypeAheadMarker> iter = typeAheadMarkers.iterator(); iter.hasNext(); ) {
            TypeAheadMarker marker = iter.next();
            Component toTest = marker.untilFocused;
            boolean match = (toTest == comp);
            while (!match && toTest != null && !(toTest instanceof Window)) {
                toTest = toTest.getParent();
                match = (toTest == comp);
            }
            if (match) {
                if (start < 0) {
                    start = marker.after;
                }
                iter.remove();
            } else if (start >= 0) {
                purgeStampedEvents(start, marker.after);
                start = -1;
            }
        }

        purgeStampedEvents(start, -1);
    }

    // Notes:
    //   * must be called inside a synchronized block
    //   * if 'start' is < 0, then this function does nothing
    //   * if 'end' is < 0, then all KeyEvents from 'start' to the end of the
    //     queue will be removed
    private void purgeStampedEvents(long start, long end) {
        if (start < 0) {
            return;
        }

        for (Iterator<KeyEvent> iter = enqueuedKeyEvents.iterator(); iter.hasNext(); ) {
            KeyEvent ke = iter.next();
            long time = ke.getWhen();

            if (start < time && (end < 0 || time <= end)) {
                iter.remove();
            }

            if (end >= 0 && time > end) {
                break;
            }
        }
    }

    
Focuses the Component before aComponent, typically based on a
FocusTraversalPolicy.
Params:
aComponent – the Component that is the basis for the focus
       traversal operation
See Also:
FocusTraversalPolicy
Component.transferFocusBackward/**
     * Focuses the Component before aComponent, typically based on a
     * FocusTraversalPolicy.
     *
     * @param aComponent the Component that is the basis for the focus
     *        traversal operation
     * @see FocusTraversalPolicy
     * @see Component#transferFocusBackward
     */
    public void focusPreviousComponent(Component aComponent) {
        if (aComponent != null) {
            aComponent.transferFocusBackward();
        }
    }

    
Focuses the Component after aComponent, typically based on a
FocusTraversalPolicy.
Params:
aComponent – the Component that is the basis for the focus
       traversal operation
See Also:
FocusTraversalPolicy
Component.transferFocus/**
     * Focuses the Component after aComponent, typically based on a
     * FocusTraversalPolicy.
     *
     * @param aComponent the Component that is the basis for the focus
     *        traversal operation
     * @see FocusTraversalPolicy
     * @see Component#transferFocus
     */
    public void focusNextComponent(Component aComponent) {
        if (aComponent != null) {
            aComponent.transferFocus();
        }
    }

    
Moves the focus up one focus traversal cycle. Typically, the focus owner
is set to aComponent's focus cycle root, and the current focus cycle
root is set to the new focus owner's focus cycle root. If, however,
aComponent's focus cycle root is a Window, then the focus owner is set
to the focus cycle root's default Component to focus, and the current
focus cycle root is unchanged.
Params:
aComponent – the Component that is the basis for the focus
       traversal operation
See Also:
Component.transferFocusUpCycle/**
     * Moves the focus up one focus traversal cycle. Typically, the focus owner
     * is set to aComponent's focus cycle root, and the current focus cycle
     * root is set to the new focus owner's focus cycle root. If, however,
     * aComponent's focus cycle root is a Window, then the focus owner is set
     * to the focus cycle root's default Component to focus, and the current
     * focus cycle root is unchanged.
     *
     * @param aComponent the Component that is the basis for the focus
     *        traversal operation
     * @see Component#transferFocusUpCycle
     */
    public void upFocusCycle(Component aComponent) {
        if (aComponent != null) {
            aComponent.transferFocusUpCycle();
        }
    }

    
Moves the focus down one focus traversal cycle. If aContainer is a focus
cycle root, then the focus owner is set to aContainer's default
Component to focus, and the current focus cycle root is set to
aContainer. If aContainer is not a focus cycle root, then no focus
traversal operation occurs.
Params:
aContainer – the Container that is the basis for the focus
       traversal operation
See Also:
Container.transferFocusDownCycle/**
     * Moves the focus down one focus traversal cycle. If aContainer is a focus
     * cycle root, then the focus owner is set to aContainer's default
     * Component to focus, and the current focus cycle root is set to
     * aContainer. If aContainer is not a focus cycle root, then no focus
     * traversal operation occurs.
     *
     * @param aContainer the Container that is the basis for the focus
     *        traversal operation
     * @see Container#transferFocusDownCycle
     */
    public void downFocusCycle(Container aContainer) {
        if (aContainer != null && aContainer.isFocusCycleRoot()) {
            aContainer.transferFocusDownCycle();
        }
    }
}