I'm noticing some weird behavior in boxart mode with a few systems, specially ones that use approximate square dimensions (GBA, NDS, PC-Engine CD...), probably because of some of the automatic settings/crops. For example if the boxart dimensions are 600 x 600 it works good. But if the file is like 600 x 598 you get some kind of stretch with extra elements in the thumbnail. Hard to explain so here's a print of Saturn (Japanese games boxes are square) and other of GBA.