Returns the dropzone at the inputed point.
        
        :param      point | <QPoint>

def dropzoneAt(self, point):
        """
        Returns the dropzone at the inputed point.
        
        :param      point | <QPoint>
        """
        for dropzone in self._dropzones:
            rect = dropzone.rect()
            if ( rect.contains(point) ):
                return dropzone
        return None