QViewHeader subclass does not repaint correctly on mac carbon

#include <QApplication>
#include <QTableWidget>
#include <QCheckBox>
#include <QBoxLayout>
#include <QHeaderView>
#include <QSize>
#include <QLineEdit>
#include <private/qheaderview_p.h>

#include <QDebug>

class LineHeaderView : public QHeaderView
{
    Q_OBJECT

    static const int FilterMargin = 4;

public:
    LineHeaderView( QWidget* parent=0 ) :
            QHeaderView(Qt::Horizontal,parent) ,
            m_filterList(),
            m_filterEditEnabled(false)
    {
    }

public slots:

    void setFilterEditEnabled( bool enabled )
    {
        if( enabled != m_filterEditEnabled)
        {
            m_filterEditEnabled = enabled;
            initializeFilterEditList();
        }
    }

protected:
    virtual void    paintSection( QPainter* painter, const QRect& rect, int logicalIndex ) const
    {
        QRect cR = captionRect(logicalIndex, rect);

        if (!rect.isValid())
            return;

        // get the state of the section
        QStyleOptionHeader opt;
        initStyleOption(&opt);

        // setup the style options structure
        opt.rect = rect;
        opt.section = logicalIndex;

        // draw caption if text is CaptionString
        opt.text = model() ? model()->headerData(logicalIndex, orientation(), Qt::DisplayRole).toString() : QString();

        QPointF oldBO = painter->brushOrigin();

        // now, draw the section
        QRegion clipRegion = painter->clipRegion();
        painter->setClipRect(opt.rect);

        // 1. draw the section background
        style()->drawControl(QStyle::CE_HeaderSection, &opt, painter, this);

        // 2.1. now draw the foreground items in the non-filter part
        opt.rect = cR;

        QStyleOptionHeader subopt = opt;
        subopt.rect = style()->subElementRect(QStyle::SE_HeaderLabel, &opt, this);
        style()->drawControl(QStyle::CE_HeaderLabel, &subopt, painter, this);
        painter->setClipRegion(clipRegion);
        painter->setBrushOrigin(oldBO);

        if( m_filterEditEnabled )
        {
            QRect filterRect = rect.adjusted(FilterMargin, cR.height(), -FilterMargin-1, -FilterMargin-1 );
            QLineEdit* le = m_filterList[logicalIndex].m_filterEdit;
            if( le )
            {
                le->setGeometry(filterRect);
                le->show();
            }
        }
    }

    virtual QSize sectionSizeFromContents( int logicalIndex ) const
    {
        // use SizeHintRole

        QVariant variant = model()->headerData(logicalIndex, orientation(), Qt::SizeHintRole);

        QStyleOptionHeader opt;
        initStyleOption(&opt);
        opt.section = logicalIndex;
        opt.text = model() ? model()->headerData(logicalIndex, orientation(), Qt::DisplayRole).toString() : QString();

        QSize sH = style()->sizeFromContents(QStyle::CT_HeaderSection, &opt, QSize(), this);

        // filter is only applied for horizontal headers...
        if( orientation() == Qt::Horizontal &&
            m_filterEditEnabled )
        {
            int h = fontMetrics().lineSpacing() + 4;
            // store caption size hint for painting
            m_filterList[logicalIndex].m_captionSizeHint = sH;
            sH.setHeight( sH.height() + h + FilterMargin );
        }
        return sH;
    }

    virtual QRect	captionRect( int logicalIndex, const QRect& sectionRect ) const
    {
        int captionHeight = m_filterEditEnabled ? m_filterList[logicalIndex].m_captionSizeHint.height() : sectionRect.height();
        return QRect(sectionRect.left(), sectionRect.top(), sectionRect.width(), captionHeight);
    }

protected slots:

    void initializeFilterEditList()
    {
        if( !m_filterEditEnabled )
        {
            for( int i=0; i<m_filterList.size(); i++ )
                m_filterList[i].m_filterEdit->deleteLater();
            m_filterList.clear();
        }
        else
        {
            while( m_filterList.size() > count() &&
                   m_filterList.size() > 0 ) // count returns -1 if no model set...
            {
                m_filterList.back().m_filterEdit->hide();
                m_filterList.back().m_filterEdit->deleteLater();
                m_filterList.pop_back();
            }
            while( m_filterList.size() < count() )
            {
                m_filterList.append( SectionFilter() );
                m_filterList.back().m_filterEdit = new QLineEdit(viewport());
                m_filterList.back().m_filterEdit->setFrame(true);
                m_filterList.back().m_filterEdit->setObjectName(QString("FLE%1").arg(m_filterList.size()-1));
            }
        }

        if( count() > 0 )
        {
            // NOTE: works very well on Windows
            headerDataChanged(orientation(),0,count()-1);
            emit geometriesChanged();

//// WORKAROUND: force update of the header on Mac OS X
//int size = sectionSize(0);
//emit sectionResized(0, size, size);

        }
        //updateFilterState();
    }


private:

    struct SectionFilter
    {
        SectionFilter():
                m_filterEdit(0),
                m_captionSizeHint()
        {
        }
        QLineEdit*	 m_filterEdit;
        mutable QSize	 m_captionSizeHint;
    };
    QList<SectionFilter>	 m_filterList;
    bool	 m_filterEditEnabled;
};




#include "main.moc"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget w;
    w.setLayout(new QBoxLayout(QBoxLayout::TopToBottom));
    QTableWidget* t = new QTableWidget(&w);
    QCheckBox* b = new QCheckBox("enable filter");
    w.layout()->addWidget(t);
    w.layout()->addWidget(b);
    LineHeaderView* fhv = new LineHeaderView(t);
    
    t->setHorizontalHeader(fhv);
    QObject::connect(b, SIGNAL(toggled(bool)), fhv, SLOT(setFilterEditEnabled(bool)));

    t->setColumnCount(5);
    t->setRowCount(3);

    QStringList sL;
    for( int i=0; i<t->columnCount(); i++ )
    {
        sL << QString("Column #%1").arg(i+1);
    }
    t->setHorizontalHeaderLabels(sL);

    w.show();
    return a.exec();
}