def _left_down(self, event):
        event.Skip()
        cal = event.GetEventObject()
        result, dt, weekday = cal.HitTest(event.GetPosition())

        if result == wx.calendar.CAL_HITTEST_DAY and not self.multi_select:
            self.single_select_day(dt)
            return

        # Inter-month-drag selection.  A quick no-movement mouse-click is
        # equivalent to a multi-select of a single day.
        if (result == wx.calendar.CAL_HITTEST_DAY
            and (not self.shift_to_select or event.ShiftDown())
            and not cal.selecting):

            self._first_date = self.date_from_datetime(dt)
            self._drag_select = [self._first_date]
            # Start showing the highlight colors with a mouse_drag event.
            self._mouse_drag(event)

        return
Handle user selection of days.
dataset/ETHPy150Open enthought/traitsui/traitsui/wx/date_editor.py/MultiCalendarCtrl._left_down