Provide an easy way to navigate to the beginning of the next or previous folder in an archive that specifies a folder structure.
Example: If the archive is set up with Folders, vol1, vol2, etc. and vol1 contains folders v1n1, v2n2, v3n3..., If the current image is vol1/v1n12/pg15.jpg, pressing ctrl-PgUp will display vol1/v1n12/pg00.jpg. Pressing ctrl-pgUp again will display vol1/v1n11/pg00.jpg. Hitting ctrl-PgDn instead (from vol1/v1n12/pg15.jpg) will display vol2/v2n01/pg00.jpg.
Bonus points for offering a browser showing the first thumbnail in each folder