void QStylePainter::drawPrimitive (QStyle::PE_IndicatorSpinDown, styleOption)

#ifndef SPINCOMBOBOX_H
#define SPINCOMBOBOX_H

#include <QSpinBox>
#include <QStyleOption>

class TStyleOptionSpinComboBox : public QStyleOptionSpinBox
{

public:

   enum { SO_SpinComboBox = SO_ComplexCustomBase + 1 };

   enum StyleOptionType { Type = SO_SpinComboBox };
   enum StyleOptionVersion { Version = 1 };

   QAbstractSpinBox::ButtonSymbols buttonSymbols;
   QAbstractSpinBox::StepEnabled stepEnabled;

   bool frame;
   bool editable;
   QRect popupRect;
   QString currentText;
   QIcon currentIcon;
   QSize iconSize;

   TStyleOptionSpinComboBox();
};

class TSpinComboBox : public QSpinBox
{
   Q_OBJECT

public:
   TSpinComboBox(QWidget *parent = 0);
   ~TSpinComboBox();


protected:

   void paintEvent(QPaintEvent *event);

private:

};

#endif // SPINCOMBOBOX_H

#include "spincombobox.h"
#include <QPainter>
#include <QStylePainter>
#include <QtDebug>

TStyleOptionSpinComboBox::TStyleOptionSpinComboBox()
:  /*QStyleOptionComplex(Version, SO_SpinComboBox),*/ buttonSymbols(QAbstractSpinBox::UpDownArrows),
   stepEnabled(QAbstractSpinBox::StepNone), frame(true), editable(false)
{
   activeSubControls = QStyle::SC_SpinBoxDown | QStyle::SC_ComboBoxArrow; // нужно ли?
}

TSpinComboBox::TSpinComboBox(QWidget *parent)
   : QSpinBox(parent)
{

}

TSpinComboBox::~TSpinComboBox()
{

}

void TSpinComboBox::paintEvent(QPaintEvent *event)
{
   TStyleOptionSpinComboBox option;
   option.initFrom(this);                                        // инициализация стиля SpinBox

   QStylePainter spainter(this);
   spainter.drawComplexControl(QStyle::CC_SpinBox, option);
   spainter.drawComplexControl(QStyle::CC_ComboBox, option);
}