#include <QtGui>
class MyComboBox : public QComboBox
{
public:
        MyComboBox (QWidget* parent):QComboBox(parent){};
        virtual void showPopup ();
};


void MyComboBox::showPopup ()
{
        if (model () && view ())
        {
                QWidget* qw = dynamic_cast<QWidget*> (view ()->parent ());
                if (qw) {
                        int myWidth = size ().width ();
                        int viewWidth = view ()->sizeHintForColumn (0);
                        qWarning() << "sizehint for column:" << viewWidth << myWidth;

                        if (count() > maxVisibleItems ()) {
                                viewWidth += style()->pixelMetric (QStyle::PM_ScrollBarExtent);
                        }
                        int maxWidth = qMax (qMin (viewWidth, 500) + 5, myWidth);
                        qWarning() << maxWidth;
                        qw->setFixedWidth (maxWidth);
                }
        }
        QComboBox::showPopup();
}

int main(int argc, char** argv)
{
        QApplication app (argc, argv);
        app.setStyle (new QCleanlooksStyle); // bud case
        //app.setStyle (new QPlastiqueStyle); // good case

        MyComboBox* comboBox = new MyComboBox (NULL);
        comboBox->setEditable (true);
        comboBox->addItem ("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");
        comboBox->addItem ("BBBBBBBBBBBBBBBBBBBBBBBBBBBB");
        qWarning() << qApp->style();
        comboBox->show();
        app.exec();
}