Making the border 100% transparent would mean it would be very difficult to know where the edges of the widget are when lining everything up on the desktop. I will add opactiy in as an option at some point, though.

Centring the "forward" and "back" buttons vertically would mean they would be in the edge of every landscape photo. The way they are currently, if you have non-square photos they are more-or-less out of the way in both portrait and landscape photos. This could be an option too.

Qole - I will look into exif rotation flags. I want to add tag filtering in a future release, which I think would enable you to get rid of wallpapers. Unfortunately, the tag cloud library (libcumulus) doesn't have headers for development available at this point