I can see what you did with having two separate tabs, but I think it would be a better interface if you can do it all in one tab. Once you've favorited or labeled shots, and look at them as shortlists, you may then want to zoom in again and look at them in detail to decide whether to exclude a shot for example. The user interface would be more straightforward. The software Photomechanic does this nicely — a very barebones interface, great for sorting and grouping pics.

Thanks, and love Picflow!