If the image set as the background with ROX-Filer is bigger than the screen's resolution and the "style" option is set to "center", the image's top left corner is on the screen's top left corner.
The intended behaviour I was waiting for was the image's center point to be at the screen's center point.
Logged In: YES
user_id=953497
Originator: YES
Sorry forgot to add infos:
ROX-Filer 2.6.1
Using ROX-All with zeroinstall
Ubuntu Feisty with everything looking normal.