Qt Override.

        Filter tab keys and process double tab keys.

def event(self, event):
        """Qt Override.

        Filter tab keys and process double tab keys.
        """
        if (event.type() == QEvent.KeyPress) and (event.key() == Qt.Key_Tab):
            self.sig_tab_pressed.emit(True)
            self.numpress += 1
            if self.numpress == 1:
                self.presstimer = QTimer.singleShot(400, self.handle_keypress)
            return True
        return QComboBox.event(self, event)