'get the bounding box in display space.'

def get_window_extent(self, renderer):

    (w, h, xd, yd, offsets) = self.get_extent_offsets(renderer)
    (px, py) = self.get_offset(w, h, xd, yd, renderer)
    return mtransforms.Bbox.from_bounds((px - xd), (py - yd), w, h)
