When setting a relative background position the positioning is relative
to the size of the area the background is applied to. Currently the
position calculation is done when the area is created, i.e. when the
background trait is set. However, at that point in time fop may not
know the bpd and ipd of the area in question. Therefore the calculated
positioning will be wrong. Am I correct in saying that the logic needs
to be changed to do that calculation (or even set the background trait)
when the layout is completed for that area and not when the area is
created in the layout process?
