Display previous albums' thumbs list

I am trying to create a block that, while displaying a picture, show me the previous album list as thumbnails.

eg:
- sub-gallery-A
--sub-sub-gallery-AA
---- image-AAA
---- image-AAB
---- image-AAC
--sub-sub-gallery-AB
--sub-sub-gallery-AC
--sub-sub-gallery-AD

While I see image-AAA, image-AAB or image-AAC, I want to see a block with thumbs of albums:
--sub-sub-gallery-AA
--sub-sub-gallery-AB
--sub-sub-gallery-AC
--sub-sub-gallery-AD

I had some help for another issue http://gallery.menalto.com/node/91399 and I guess there will be something similar but can't find out how to solve it

any help?