Minimum width is the total width + margins, minimum height
        is the largest height.

def get_minimum_size(self, data):
        """Minimum width is the total width + margins, minimum height
        is the largest height."""
        width = 0
        min_height = 0
        for element in self.elements:
            size = element.get_minimum_size(data)
            min_height = max(min_height, size.y)
            width += size.x
        width += (len(self.elements)-1)*self.margin
        return datatypes.Point(width, min_height)