code: def get_pan_rect(self):
          
          wd, ht = self.get_window_size()
          #win_pts = np.asarray([(0, 0), (wd-1, 0), (wd-1, ht-1), (0, ht-1)])
          win_pts = np.asarray([(0, 0), (wd, 0), (wd, ht), (0, ht)])
          arr_pts = self.tform['data_to_window'].from_(win_pts)
          return arr_pts
docs: Get the coordinates in the actual data corresponding to the
          area shown in the display for the current zoom level and pan.
  
          Returns
          -------
          points : list
              Coordinates in the form of
              ``[(x0, y0), (x1, y1), (x2, y2), (x3, y3)]``
              from lower-left to lower-right.