Returns the date at the inputed x position.
        
        :return     <QDate>

def dateAt(self, x):
        """
        Returns the date at the inputed x position.
        
        :return     <QDate>
        """
        gantt       = self.ganttWidget()
        dstart      = gantt.dateStart()
        days        = int(x / float(gantt.cellWidth()))
        
        return dstart.addDays(days)