diff --git a/keduvocdocument/keduvoclessonmodel.cpp b/keduvocdocument/keduvoclessonmodel.cpp
index d9508b5..f4da18d 100644
--- a/keduvocdocument/keduvoclessonmodel.cpp
+++ b/keduvocdocument/keduvoclessonmodel.cpp
@@ -1,115 +1,121 @@
 /***************************************************************************
 
     Copyright 2008-2009 Frederik Gladhorn <gladhorn@kde.org>
 
  ***************************************************************************/
 
 /***************************************************************************
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
  *   it under the terms of the GNU General Public License as published by  *
  *   the Free Software Foundation; either version 2 of the License, or     *
  *   (at your option) any later version.                                   *
  *                                                                         *
  ***************************************************************************/
 
 #include "keduvoclessonmodel.h"
 
 #include <KRandom>
 #include <KLocalizedString>
 #include <QtGui/QFont>
 
 /** @file
   * Implementation of LessonModel.
   * Functions to create the model from the lessons of the vocabulary document.
   */
 
 
 KEduVocLessonModel::KEduVocLessonModel(QObject * parent)
     : KEduVocContainerModel(KEduVocContainer::Lesson, parent)
+    , d(0)
 {
 }
 
+KEduVocLessonModel::~KEduVocLessonModel()
+{
+    delete d;
+}
+
 KEduVocContainer * KEduVocLessonModel::rootContainer() const
 {
     if (!getDoc()) {
         return 0;
     }
     return getDoc()->lesson();
 }
 
 Qt::ItemFlags KEduVocLessonModel::flags(const QModelIndex &index) const
 {
     if (index.isValid() && index.parent() == QModelIndex()) {
         return (Qt::ItemIsEnabled
                 | Qt::ItemIsEditable
                 | Qt::ItemIsSelectable);
     }
 
     // the name column should be checkable to select lessons for practice
     return  KEduVocContainerModel::flags(index);
 }
 
 QVariant KEduVocLessonModel::data(const QModelIndex & index, int role) const
 {
     if (index.isValid() && !index.parent().isValid()) {
         if (index.column() == 0) {
             switch (role) {
             case Qt::DisplayRole:
                 return i18nc("display of the name of the vocabulary collection", "Collection: %1", KEduVocContainerModel::data(index, role).toString());
             case Qt::FontRole:
                 QFont f;
                 f.setBold(true);
                 return f;
             }
         }
     }
     return KEduVocContainerModel::data(index, role);
 }
 
 bool KEduVocLessonModel::setData(const QModelIndex &index, const QVariant &value, int role)
 {
     if (index.isValid() && !index.parent().isValid()) {
         if (index.column() == ContainerNameColumn && role == Qt::EditRole) {
             ///@todo decouple the root lesson and document title
             getDoc()->setTitle(value.toString());
         }
     }
     return KEduVocContainerModel::setData(index, value, role);
 }
 
 void KEduVocLessonModel::splitLesson(const QModelIndex& containerIndex, int entriesPerLesson, SplitLessonOrder order)
 {
     if (!containerIndex.isValid()) {
         return;
     }
 
     if (static_cast<KEduVocContainer*>(containerIndex.internalPointer())->containerType() != KEduVocContainer::Lesson) {
         return;
     }
 
     KEduVocLesson* parentLesson = static_cast<KEduVocLesson*>(containerIndex.internalPointer());
 
     int numNewLessons = parentLesson->entryCount() / entriesPerLesson;
     // modulo - fraction lesson if not 0 we need one more
     if (parentLesson->entryCount() % entriesPerLesson) {
         numNewLessons++;
     }
 
     while (parentLesson->entryCount() > 0) {
         beginInsertRows(containerIndex, parentLesson->entryCount(), parentLesson->entryCount());
         KEduVocLesson* child = new KEduVocLesson(parentLesson->name()
                 + QString(" %1").arg(parentLesson->childContainerCount() + 1), parentLesson);
         parentLesson->appendChildContainer(child);
         endInsertRows();
 
         while (parentLesson->entryCount() > 0 && child->entryCount() < entriesPerLesson) {
             // next entry to be assigned to one of the new lessons
             int nextEntry = 0;
             if (order == Random) {
                 nextEntry = KRandom::random() % parentLesson->entryCount();
                 child->appendEntry(parentLesson->entry(nextEntry));
             }
         }
     }
 }
diff --git a/keduvocdocument/keduvoclessonmodel.h b/keduvocdocument/keduvoclessonmodel.h
index bf9b123..e854e44 100644
--- a/keduvocdocument/keduvoclessonmodel.h
+++ b/keduvocdocument/keduvoclessonmodel.h
@@ -1,55 +1,60 @@
 /***************************************************************************
 
     Copyright 2008-2009 Frederik Gladhorn <gladhorn@kde.org>
 
  ***************************************************************************/
 
 /***************************************************************************
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
  *   it under the terms of the GNU General Public License as published by  *
  *   the Free Software Foundation; either version 2 of the License, or     *
  *   (at your option) any later version.                                   *
  *                                                                         *
  ***************************************************************************/
 
 #ifndef KEDUVOCLESSONMODEL_H
 #define KEDUVOCLESSONMODEL_H
 
 #include "keduvoccontainermodel.h"
 
 /**
   * Model for the tree of lessons.
   */
 class KEduVocLessonModel : public KEduVocContainerModel
 {
     Q_OBJECT
 
 public:
     /** When splitting a lesson into smaller ones - how to sort the entries into lessons.*/
     enum SplitLessonOrder {
         Sorted,    /**< The order of the entries in the document */
         Random /**< Randomized */
     };
 
     explicit KEduVocLessonModel(QObject *parent = 0);
+    ~KEduVocLessonModel();
 
     virtual Qt::ItemFlags flags(const QModelIndex &index) const;
     virtual QVariant data(const QModelIndex &index, int role) const;
     virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
 
     /**
      * Divide a lesson into smaller ones.
      * Tip: If you create a lesson that is >= the original one and use random order, you get your lesson reshuffled. Maybe that is sometimes useful. For now the lessons are appended at the end.
      * @param lessonIndex lesson to split
      * @param entriesPerLesson number of entries in each new lesson
      * @param order one of SplitLessonOrder
         */
     void splitLesson(const QModelIndex& containerIndex, int entriesPerLesson, SplitLessonOrder order);
 
 protected:
     KEduVocContainer * rootContainer() const;
+
+private:
+    class Private;
+    Private * const d;
 };
 
 
 #endif