def mousePressEvent(self, e):
        """
        Starts selecting
        """
        self._selecting = True
        self._sel_start = e.pos().y()
        start = end = TextHelper(self.editor).line_nbr_from_position(
            self._sel_start)
        self._start_line = start
        TextHelper(self.editor).select_lines(start, end)
Starts selecting