diff -r dee5afe5301f -r 3f74d0d4af4c doc/src/snippets/signalsandslots/signalsandslots.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/src/snippets/signalsandslots/signalsandslots.cpp	Thu Apr 08 14:19:33 2010 +0300
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QAbstractButton>
+
+#include "signalsandslots.h"
+
+//! [0]
+void Counter::setValue(int value)
+{
+    if (value != m_value) {
+        m_value = value;
+        emit valueChanged(value);
+    }
+}
+//! [0]
+
+int main()
+{
+//! [1]
+    Counter a, b;
+//! [1] //! [2]
+    QObject::connect(&a, SIGNAL(valueChanged(int)),
+                     &b, SLOT(setValue(int)));
+//! [2]
+
+//! [3]
+    a.setValue(12);     // a.value() == 12, b.value() == 12
+//! [3] //! [4]
+    b.setValue(48);     // a.value() == 12, b.value() == 48
+//! [4]
+
+
+    QWidget *widget = reinterpret_cast<QWidget *>(new QObject(0));
+//! [5]
+    if (widget->inherits("QAbstractButton")) {
+        QAbstractButton *button = static_cast<QAbstractButton *>(widget);
+        button->toggle();
+//! [5] //! [6]
+    }
+//! [6]
+
+//! [7]
+    if (QAbstractButton *button = qobject_cast<QAbstractButton *>(widget))
+        button->toggle();
+//! [7]
+}