def selection_range(self):
        """
        :rtype: int, int, int, int
        """
        selected = self.selectionModel().selection()
        """:type: QItemSelection """

        if selected.isEmpty():
            return -1, -1, -1, -1

        min_row = numpy.min([rng.top() for rng in selected])
        max_row = numpy.max([rng.bottom() for rng in selected])
        start = numpy.min([rng.left() for rng in selected])
        end = numpy.max([rng.right() for rng in selected]) + 1

        return min_row, max_row, start, end
:rtype: int, int, int, int