Problems when you do not actually want any kind of custom order:
- An auxiliary file .XnViewSort is created which can "dirty" your pretty collection of images.
- I don't usually care about Custom orders. I do not use them, period. But I drag and drop files in order to move/copy files quite frequently. The problem here is that if you abort the drag and drop action (by just dropping the file on the file list, even if you do in its very same original place), XnView MP always creates a Custom order (and its associated "dirty" file). (And please remember this issue).