Design feedback v2

ED: why it's not possible to add packages if image is not built? As far as I understood user should be able to add packages from other layers. I agree it's a bit tricky to add packages to the unknown set, but still.

ED: Would it make sense to show only built images in the list of base images for customization? It would simplify UI even more. We are forcing user to build an image to be able to customize it. Why not go further and make the procedure even more simpler?

ED: What does it mean 'Package size'? Is it image size or something else?

ED: What about editing of .bb files?