[Image-SIG] Transparent Gif

[Takekun Sato]

I would like to make transparent Gif image.
I tested following code but failed to make transparent pixels.
If you know anything, please let me know.
(platform: PIL1.1.1, Python2.0, Win2K)
-----
import Image;
im=Image.new("P",(100,100),0);
im.putpalette([0,0,0,128,128,128]);
for i in range(20,80):
  for j in range(20,40):
    im.putpixel((i,j),1);
im.save("C:/tmp/test.gif",transparency=1);