def METHOD_NAME(self, event):
    if event.button() == Qt.LeftButton:
        for recordIndex, rect in self._optionsRects.items():
            if QRect(*rect).contains(event.pos()):
                self._clickedIndex = recordIndex
                self._oldSelection = self._selection
                self._selection = {recordIndex}
                if (
                    self._selectionMode > 1
                    and QApplication.keyboardModifiers() & Qt.ShiftModifier
                ):
                    shiftSelection = self._selection ^ self._oldSelection
                    if shiftSelection:
                        self._selection = shiftSelection
                else:
                    self._selection |= self._oldSelection
                break
        self.update()
    else:
        super().METHOD_NAME(event)