Sets the endiing date time for this gantt chart.
        
        :param      dtime | <QDateTime>

def setDateTimeEnd(self, dtime):
        """
        Sets the endiing date time for this gantt chart.
        
        :param      dtime | <QDateTime>
        """
        self._dateEnd = dtime.date()
        
        if self.timescale() in (self.Timescale.Minute, self.Timescale.Hour):
            self._timeEnd = dtime.time()
        else:
            self._timeEnd = QTime(23, 59, 59)