--- a/src/share/classes/com/sun/java/swing/plaf/windows/WindowsRootPaneUI.java	Wed Nov 12 13:02:00 2014 +0300
+++ b/src/share/classes/com/sun/java/swing/plaf/windows/WindowsRootPaneUI.java	Fri Nov 14 18:12:56 2014 +0400
@@ -31,6 +31,8 @@
 import java.awt.KeyEventPostProcessor;
 import java.awt.Window;
 import java.awt.Toolkit;
+
+import sun.awt.AWTAccessor;
 import sun.awt.SunToolkit;
 
 import java.awt.event.ActionEvent;
@@ -133,10 +135,15 @@
                 // window. If this time appears to be greater than the altRelease
                 // event time the event is skipped to avoid unexpected menu
                 // activation. See 7121442.
+                // Also we must ensure that original source of key event belongs
+                // to the same window object as winAncestor. See 8001633.
                 boolean skip = false;
                 Toolkit tk = Toolkit.getDefaultToolkit();
                 if (tk instanceof SunToolkit) {
-                    skip = ev.getWhen() <= ((SunToolkit)tk).getWindowDeactivationTime(winAncestor);
+                    Component originalSource = AWTAccessor.getKeyEventAccessor()
+                            .getOriginalSource(ev);
+                    skip = SunToolkit.getContainingWindow(originalSource) != winAncestor ||
+                            ev.getWhen() <= ((SunToolkit) tk).getWindowDeactivationTime(winAncestor);
                 }
 
                 if (menu != null && !skip) {

--- a/src/share/classes/java/awt/event/KeyEvent.java	Wed Nov 12 13:02:00 2014 +0300
+++ b/src/share/classes/java/awt/event/KeyEvent.java	Fri Nov 14 18:12:56 2014 +0400
@@ -930,6 +930,10 @@
                                                long extendedKeyCode) {
                     ev.extendedKeyCode = extendedKeyCode;
                 }
+
+                public Component getOriginalSource( KeyEvent ev ) {
+                    return ev.originalSource;
+                }
             });
     }
 
@@ -939,6 +943,14 @@
      */
     private static native void initIDs();
 
+    /**
+     * The original event source.
+     *
+     * Event source can be changed during processing, but in some cases
+     * we need to be able to obtain original source.
+     */
+    private Component originalSource;
+
     private KeyEvent(Component source, int id, long when, int modifiers,
                     int keyCode, char keyChar, int keyLocation, boolean isProxyActive) {
         this(source, id, when, modifiers, keyCode, keyChar, keyLocation);
@@ -1023,6 +1035,7 @@
         } else if ((getModifiers() == 0) && (getModifiersEx() != 0)) {
             setOldModifiers();
         }
+        originalSource = source;
     }
 
     /**

--- a/src/share/classes/sun/awt/AWTAccessor.java	Wed Nov 12 13:02:00 2014 +0300
+++ b/src/share/classes/sun/awt/AWTAccessor.java	Fri Nov 14 18:12:56 2014 +0400
@@ -650,6 +650,11 @@
          * Sets extendedKeyCode field for KeyEvent
          */
         void setExtendedKeyCode(KeyEvent ev, long extendedKeyCode);
+
+        /**
+         * Gets original source for KeyEvent
+         */
+        Component getOriginalSource(KeyEvent ev);
     }
 
     /**

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/javax/swing/plaf/windows/WindowsRootPaneUI/AltKeyProccessingNPETest/AltKeyProccessingNPETest.java	Fri Nov 14 18:12:56 2014 +0400
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2014, 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.
+ *
+ * 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.
+ */
+
+/* @test
+   @bug 8001633
+   @summary Wrong alt processing during switching between windows
+   @author mikhail.cherkasov@oracle.com
+   @run main AltKeyProccessingNPETest
+*/
+import sun.awt.SunToolkit;
+
+import java.awt.*;
+import java.awt.event.KeyEvent;
+import javax.swing.UIManager;
+
+public class AltKeyProccessingNPETest {
+
+    private static Robot robot;
+
+    public static void initRobot() throws AWTException {
+        robot = new Robot();
+        robot.setAutoDelay(100);
+    }
+
+    public static void sync() {
+        SunToolkit toolkit = (SunToolkit) Toolkit.getDefaultToolkit();
+        toolkit.realSync();
+    }
+
+    public static void main(String args[]) throws Exception {
+
+        initRobot();
+
+        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
+
+        Frame frame = new Frame();
+        frame.setSize(400,400);
+        frame.setVisible(true);
+
+        sync();
+
+        robot.keyPress(KeyEvent.VK_ALT);
+        robot.keyRelease(KeyEvent.VK_ALT);
+    }
+}
\ No newline at end of file