The new version: 1.3.1
I tested the new possibility to create subalbums, like this:
gallery A under album A
gallery B under album B
album Z contains albums A and B.
My first page (album=Z,extend) shows 2 rectangles with text, but without previews of the pictures of both albums A and B.
The admin page (edit Album) gives you the possibility to give it a name, a description and a preview image. This image, whatever you choose, is not remembered by NGG.
Or am I doing something wrong?