Changes the current date to the clicked on date.
        
        :param      event | <QMousePressEvent>

def mousePressEvent( self, event ):
        """
        Changes the current date to the clicked on date.
        
        :param      event | <QMousePressEvent>
        """
        XPopupWidget.hideToolTip()
        
        # update the current date
        self.setCurrentDate(self.dateAt(event.scenePos()))
        
        super(XCalendarScene, self).mousePressEvent(event)