The blue folders are used to merge the content of several other folders together.
This allows DeskBar to show items from 4 different locations:
- /system
- /system/non-packaged
- /home/config
- /home/config/non-packaged
So you can have a mix of “automatic” entries (included in packages, they will appear when you install the package and disappear when you uninstall the package), and “manual” entries (that you create yourself, or for example if you install old BeOS apps using the legacy softwarevalet package installer).
They are a kind of extended symlinks that can point to multiple places. But these places are just plain standard directories.
That being said, this has nothing to do with the folder icons. We could certainly add the icons to the underlying folders, not sure why that’s missing, it looks like an oversight. Then I’m not sure if the icon will be “transferred” to the “blue folder”, but we can make that happen, too. It’s just a matter of someone writing the code to make it work.