diff --git a/libs/flake/KoShapeGroup.h b/libs/flake/KoShapeGroup.h
index fba4d03f8e..0755d7be9e 100644
--- a/libs/flake/KoShapeGroup.h
+++ b/libs/flake/KoShapeGroup.h
@@ -1,80 +1,83 @@
 /* This file is part of the KDE project
  * Copyright (C) 2006 Thomas Zander <zander@kde.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library 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
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef KOSHAPEGROUP_H
 #define KOSHAPEGROUP_H
 
 #include "KoShapeContainer.h"
 
 #include <QList>
 
 #include "kritaflake_export.h"
 
 class KoShapeSavingContext;
 class KoShapeLoadingContext;
 class KoShapeGroupPrivate;
 
 /**
  * Provide grouping for shapes.
  * The group shape allows you to add children which will then be grouped in selections
  * and actions.
  * <p>If you have a set of shapes that together make up a bigger shape it is often
  * useful to group them together so the user will perceive the different shapes as
  * actually being one.  This means that if the user clicks on one shape, all shapes
  * in the group will be selected at once, making the tools that works on
  * selections alter all of them at the same time.
+ *
  * <p>Note that while this object is also a shape, it is not actually visible and the user
  * can't interact with it.
+ *
+ * <p>WARNING: this class is NOT threadsafe, it caches the size in an unsafe way
  */
 class KRITAFLAKE_EXPORT KoShapeGroup : public KoShapeContainer
 {
 public:
     /// Constructor
     KoShapeGroup();
     /// destructor
     virtual ~KoShapeGroup();
     /// This implementation is empty since a group is itself not visible.
     virtual void paintComponent(QPainter &painter, const KoViewConverter &converter, KoShapePaintingContext &paintcontext);
     /// always returns false since the group itself can't be selected or hit
     virtual bool hitTest(const QPointF &position) const;
     /// a group in flake doesn't have a size, this function just returns QSizeF(0,0)
     virtual QSizeF size() const;
     /// a group's boundingRect
     virtual QRectF boundingRect() const;
     /// reimplemented from KoShape
     virtual void saveOdf(KoShapeSavingContext &context) const;
     // reimplemented
     virtual bool loadOdf(const KoXmlElement &element, KoShapeLoadingContext &context);
 
     /**
      * @brief Invalidate the size cache of the group
      *
      * The group shape caches the size of itself as it can be quite expensive to recalculate
      * the size if there are a lot of subshapes. This function is called when the cache needs
      * to be invalidated.
      */
     void invalidateSizeCache();
 
 private:
     virtual void shapeChanged(ChangeType type, KoShape *shape = 0);
 
     Q_DECLARE_PRIVATE(KoShapeGroup)
 };
 
 #endif