Overloads the set rect method to signal that the scene needs to be 
        rebuilt.
        
        :param      args | <arg variant>

def setSceneRect(self, *args):
        """
        Overloads the set rect method to signal that the scene needs to be 
        rebuilt.
        
        :param      args | <arg variant>
        """
        curr = self.sceneRect()
        
        super(XGanttScene, self).setSceneRect(*args)
        
        if curr != QRectF(*args):
            self._dirty = True