Implement open pages classes to handle doc files like edit mode.

Based on the implementation done by ck, slightly modified and thus put
under the private help internal namespace.

src/plugins/help/openpageswidget.h

@@ -0,0 +1,83 @@
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).
+**
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** Commercial Usage
+**
+** Licensees holding valid Qt Commercial licenses may use this file in
+** accordance with the Qt Commercial License Agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Nokia.
+**
+** 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.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://qt.nokia.com/contact.
+**
+**************************************************************************/
+
+#ifndef OPENPAGESWIDGET_H
+#define OPENPAGESWIDGET_H
+
+#include <QtGui/QStyledItemDelegate>
+#include <QtGui/QTreeView>
+
+namespace Help {
+    namespace Internal {
+
+class OpenPagesModel;
+
+class OpenPagesDelegate : public QStyledItemDelegate
+{
+    Q_OBJECT
+
+public:
+    explicit OpenPagesDelegate(QObject *parent = 0);
+
+    void paint(QPainter *painter, const QStyleOptionViewItem &option,
+        const QModelIndex &index) const;
+
+    mutable QModelIndex pressedIndex;
+};
+
+class OpenPagesWidget : public QTreeView
+{
+    Q_OBJECT
+
+public:
+    OpenPagesWidget(OpenPagesModel *model);
+    ~OpenPagesWidget();
+
+signals:
+    void setCurrentPage(const QModelIndex &index);
+
+    void closePage(const QModelIndex &index);
+    void closePagesExcept(const QModelIndex &index);
+
+private slots:
+    void contextMenuRequested(QPoint pos);
+    void handlePressed(const QModelIndex &index);
+    void handleClicked(const QModelIndex &index);
+
+private:
+    bool eventFilter(QObject *obj, QEvent *event);
+
+private:
+    OpenPagesDelegate *m_delegate;
+};
+
+    } // namespace Internal
+} // namespace Help
+
+#endif // OPENPAGESWIDGET_H