Bit depth in line

I've just been trying to learn Python using "How to think like a Computer Scientist". I reached this point where it refers to GASP and provides examples:

http://openbookproject.net//thinkCSpy/chap04.xhtml

Unfortunately Gasp wasn't included in the Ubuntu Python so went to FAQ 31 here, had a few false starts downloadinf and installing, but finally did.

Then tried the first example on that page above, and the circle drew and the box drew but the line errored out with:

>>> Line((100, 400), (580, 200))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.5/site-packages/gasp/api.py", line 87, in __init__
    backend.create_line(self)
  File "/usr/lib/python2.5/site-packages/gasp/backend.py", line 180, in create_line
    (end[0], flip_coords(end[1], obj.sprite.rect)), False)
ValueError: unsupported bit depth for aaline draw (supports 32 & 24 bit)

I don't know if this applies but I use a Thinkpad 600E and it has its graphics mode set to 16 bit color -- I have to do that to be able to run reasonably fast in Ubuntu. Please don't obsolete people like us in the name of graphics progress! -- other than GASP's line drawing function, I haven't had a single problem running anything else in Ubuntu -- including videos, and a VMware virtual machine for win98se.

In fact your box and circle drew fine -- only the line had this problem -- if GASP is simple old-style graphics for educational purposes, seems like even 8 bit color ought to work! :) (I used to use a TRS-80, and an Amiga, so I remember -- well, of course even the IBM-PC CGA back then.) Do we really need 24 million shades for a simple line? I don't mind choosing from 65535.

Thanks!