Identification of pictures that are not in a collection
I have a very big catalogue, and basically all my pictures should be in at least one collection. But sometimes I forget to make an assignment after import, and then it is quite difficult to identify these pictures later. Also copies that are created by editing in external apps are not automatically assigned to a collection even if the original picture was assigned.
It would be a perfect solution to create a smart collection for these cases, but I still could not figure out, if/how it is possible to create such a smart collection.

