Image gallery organization? Thread

With my previous mod, I added a whole lot of images and after a while, the image gallery felt like a complete mess. So is there a way to have ingame shots in one gallery, model shots in another, concepts in another?

Does the image type do something? Should I be able to sort the images by the type? And why I'm not able to write my own types for the images? Most of the types in the list are a bit too obscure for me.