It's impossible to select a specific image as a thumbnail for a main album, because all my pictures are located in subalbums some levels below the main album. To make it more clear, please have a look on the structure of my gallery:
North America -> Usa -> Arizona -> Petrified Forest
North America -> Usa -> Arizona -> Misc
North America -> Usa -> Arizona -> White Pocket
...
The albums "North America", "Usa" and "Arizona" does not contain any single picture, just the subalbums. All those pictures are located in the subalbums Petrified Forest, Misc, White Pocket and so on. In the options dialog within the admin section, I do not have the possibility to select a thumbnail for "North America", "Usa" and "Arizona". Before changeset 1020 was released, the first picture of the first subalbum was automatically taken for that. Now I get random pictures as thumbs for the album "North America", "Usa" and "Arizona", which I do not want.
Just in case you don't understand, please go on my gallery: http://www.synnatschke.com/gallery and press the refresh button in your browser. You will get then random thumbs for all main albums, like "North America"...