diff --git a/src/KGantt/kganttdatetimegrid.h b/src/KGantt/kganttdatetimegrid.h
index 1b19274..93eb995 100644
--- a/src/KGantt/kganttdatetimegrid.h
+++ b/src/KGantt/kganttdatetimegrid.h
@@ -1,168 +1,169 @@
 /*
  * Copyright (C) 2001-2015 Klaralvdalens Datakonsult AB.  All rights reserved.
  *
  * This file is part of the KGantt library.
  *
  * 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.
  *
  * This program 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 General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef KGANTTDATETIMEGRID_H
 #define KGANTTDATETIMEGRID_H
 
 #include "kganttabstractgrid.h"
 
 #include <QDateTime>
 #include <QSet>
+#include <QPair>
 
 namespace KGantt {
 
     class DateTimeScaleFormatter;
     class DateTimeTimeLine;
 
     class KGANTT_EXPORT DateTimeGrid : public AbstractGrid
     {
         Q_OBJECT
         KGANTT_DECLARE_PRIVATE_DERIVED( DateTimeGrid )
     public:
         enum Scale {
             ScaleAuto, 
             ScaleHour,
             ScaleDay,
             ScaleWeek,
             ScaleMonth,
             ScaleUserDefined
         };
 	
         DateTimeGrid();
         virtual ~DateTimeGrid();
 
         QDateTime startDateTime() const;
         void setStartDateTime( const QDateTime& dt );
 
         qreal dayWidth() const;
         void setDayWidth( qreal );
 
         qreal mapFromDateTime( const QDateTime& dt) const;
         QDateTime mapToDateTime( qreal x ) const;
 
         void setWeekStart( Qt::DayOfWeek );
         Qt::DayOfWeek weekStart() const;
 
         void setFreeDays( const QSet<Qt::DayOfWeek>& fd );
         QSet<Qt::DayOfWeek> freeDays() const;
 
         void setFreeDaysBrush(const QBrush brush);
         QBrush freeDaysBrush() const;
 
         void setScale( Scale s );
         Scale scale() const;
 
         void setUserDefinedLowerScale( DateTimeScaleFormatter* lower );
         void setUserDefinedUpperScale( DateTimeScaleFormatter* upper );
         DateTimeScaleFormatter* userDefinedLowerScale() const;
         DateTimeScaleFormatter* userDefinedUpperScale() const;
 
         bool rowSeparators() const;
         void setRowSeparators( bool enable );
 
         void setNoInformationBrush( const QBrush& brush );
         QBrush noInformationBrush() const;
 
         /*reimp*/ Span mapToChart( const QModelIndex& idx ) const Q_DECL_OVERRIDE;
         /*reimp*/ bool mapFromChart( const Span& span, const QModelIndex& idx,
                                      const QList<Constraint>& constraints=QList<Constraint>() ) const Q_DECL_OVERRIDE;
         /*reimp*/ qreal mapToChart( const QVariant& value ) const Q_DECL_OVERRIDE;
         /*reimp*/ QVariant mapFromChart( qreal x ) const Q_DECL_OVERRIDE;
         /*reimp*/ void paintGrid( QPainter* painter, 
                                   const QRectF& sceneRect, const QRectF& exposedRect,
                                   AbstractRowController* rowController = nullptr,
                                   QWidget* widget = nullptr ) Q_DECL_OVERRIDE;
         /*reimp*/ void paintHeader( QPainter* painter, 
                                     const QRectF& headerRect, const QRectF& exposedRect,
                                     qreal offset, QWidget* widget = nullptr ) Q_DECL_OVERRIDE;
 
         DateTimeTimeLine *timeLine() const;
 
     protected:
         virtual void paintHourScaleHeader( QPainter* painter, 
                            const QRectF& headerRect, const QRectF& exposedRect,
                            qreal offset, QWidget* widget = nullptr );
         virtual void paintDayScaleHeader( QPainter* painter, 
                           const QRectF& headerRect, const QRectF& exposedRect,
                           qreal offset, QWidget* widget = nullptr );
         virtual void paintWeekScaleHeader( QPainter* painter,
                                            const QRectF& headerRect, const QRectF& exposedRect,
                                            qreal offset, QWidget* widget = nullptr );
         virtual void paintMonthScaleHeader( QPainter* painter,
                                             const QRectF& headerRect, const QRectF& exposedRect,
                                             qreal offset, QWidget* widget = nullptr );
 
         virtual void paintUserDefinedHeader( QPainter* painter, 
                                      const QRectF& headerRect, const QRectF& exposedRect, 
                                      qreal offset, const DateTimeScaleFormatter* formatter, 
                                      QWidget* widget = nullptr );
 
         virtual void drawDayBackground(QPainter* painter, const QRectF& rect, const QDate& date);
         virtual void drawDayForeground(QPainter* painter, const QRectF& rect, const QDate& date);
         
         QRectF computeRect(const QDateTime& from, const QDateTime& to, const QRectF& rect) const;
         QPair<QDateTime, QDateTime> dateTimeRange(const QRectF& rect) const;
 
         /* reimp */ void drawBackground(QPainter* paint, const QRectF& rect) Q_DECL_OVERRIDE;
         /* reimp */ void drawForeground(QPainter* paint, const QRectF& rect) Q_DECL_OVERRIDE;
     };
 
     class KGANTT_EXPORT DateTimeScaleFormatter
     {
         KGANTT_DECLARE_PRIVATE_BASE_POLYMORPHIC( DateTimeScaleFormatter )
     public:
         enum Range {
             Second,
             Minute,
             Hour,
             Day,
             Week,
             Month,
             Year
         };
 
         DateTimeScaleFormatter( Range range, const QString& formatString,
                                 Qt::Alignment alignment = Qt::AlignCenter );
         DateTimeScaleFormatter( Range range, const QString& formatString,
                                 const QString& templ, Qt::Alignment alignment = Qt::AlignCenter );
         DateTimeScaleFormatter( const DateTimeScaleFormatter& other );
         virtual ~DateTimeScaleFormatter();
 
         DateTimeScaleFormatter& operator=( const DateTimeScaleFormatter& other );
 
         QString format() const;
         Range range() const;
         Qt::Alignment alignment() const;
 
         virtual QDateTime nextRangeBegin( const QDateTime& datetime ) const;
         virtual QDateTime currentRangeBegin( const QDateTime& datetime ) const;
 
         QString format( const QDateTime& datetime ) const;
         virtual QString text( const QDateTime& datetime ) const;
     };
 }
 
 
 
 #ifndef QT_NO_DEBUG_STREAM
 QDebug KGANTT_EXPORT operator<<( QDebug dbg, KGantt::DateTimeScaleFormatter::Range );
 #endif
 
 #endif /* KGANTTDATETIMEGRID_H */