While testing Atelier 1.0.255 I noticed that the namespace subtree of my Atelier project used different icon shading for the top-level Classes folder compared with the top-level Routines one:
Drilling down into parts of the Wasabi package helped me work out the significance of white-filled icons versus brown-filled ones:
A package is white if there are no classes in it, but only subpackages.
As a footnote, this only happens when browsing the namespace within Atelier Explorer. If you do the same on the Server Explorer view, all the packages are brown - another puzzling inconsistency between these two views: