Doc: Fix documentation warnings for Qt Widgets

- Exclude forwarding headers to Qt GUI as they caused the headers
  to be parsed twice.
- Drop documentation for removed example

Task-number: QTBUG-86295
Change-Id: I08eb46b7c7f813f103cc545f931896be99a3ccec
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

examples/widgets/doc/src/boxes.qdoc

@@ -1,48 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2016 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the documentation of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:FDL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Free Documentation License Usage
-** Alternatively, this file may be used under the terms of the GNU Free
-** Documentation License version 1.3 as published by the Free Software
-** Foundation and appearing in the file included in the packaging of
-** this file. Please review the following information to ensure
-** the GNU Free Documentation License version 1.3 requirements
-** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
-    \example graphicsview/boxes
-    \title Boxes
-    \ingroup examples-graphicsview
-    \brief Combines advanced OpenGL rendering with the Graphics View framework.
-
-    \image boxes-demo.png
-
-    Elements in the demo can be controlled using the mouse in the following
-    ways:
-    \list
-        \li Dragging the mouse while pressing the left mouse button rotates the
-           box in the center.
-        \li Dragging the mouse while pressing the right mouse button rotates the
-           satellite boxes.
-        \li Scrolling the mouse wheel zooms in and out of the scene.
-    \endlist
-
-    The options pane can be used to fine-tune various parameters in the demo,
-    including colors and pixel shaders.
-*/

src/widgets/doc/qtwidgets.qdocconf

@@ -48,6 +48,15 @@ excludedirs += snippets
 # Included in qttestlib.qdocconf instead
 excludefiles += ../kernel/qtestsupport_widgets.cpp
 
+# Exclude forwarding headers to QtGUI to avoid duplicates in the node tree
+excludefiles += \
+    ../dialogs/qfilesystemmodel.h \
+    ../kernel/qaction.h \
+    ../kernel/qactiongroup.h \
+    ../kernel/qshortcut.h \
+    ../util/qundogroup.h \
+    ../util/qundostack.h
+
 imagedirs   += images \
                ../../../doc/src/images \
                ../../../examples/widgets/doc/images \

src/widgets/kernel/qwidget.cpp

@@ -12493,7 +12493,7 @@ QWidget *QWidget::keyboardGrabber()
     does not allow an application to interrupt what the user is currently
     doing in another application.
 
-    \sa isActiveWindow(), window(), show(), QWindowsWindowFunctions::setWindowActivationBehavior()
+    \sa isActiveWindow(), window(), show()
 */
 void QWidget::activateWindow()
 {