Fusion style does not draw check boxes in combo box

QStandardItemModel *filerModel = new QStandardItemModel();
QStandardItem *firstFilterItem = new QStandardItem(QString("Event Filter"));

firstFilterItem->setFlags(Qt::ItemIsEnabled);
filerModel->appendRow(firstFilterItem);

QVector< EventType > filterList;
filterList << StateChanged << NameChanged << DescriptionChanged << Window << Focus << Document << Object << Text << Table << Others;
for(int i = 0; i < filterList.count(); ++i) {
    EventType t = filterList[i];
    QStandardItem* item = new QStandardItem(eventName(t));
    item->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled);
    item->setData(QVariant::fromValue<EventType>(t), EventsModel::EventTypeRole);
    item->setData(Qt::Checked, Qt::CheckStateRole);
    filerModel->appendRow(QList<QStandardItem*>() << item);
}

m_ui.filterComboBox->setModel(filerModel);