[GRASS-dev] v.overlay: countries and oceans problem

Hi,

I tried to add oceans to the world country map "admin98" from
http://mappinghacks.com/data/admin98.zip

in a latlong location by

g.region n=90N s=90S w=180W e=180E res=0:05 -p
v.in.region worldbox
v.db.addtable worldbox col="area varchar(10)"
v.db.update worldbox col=area val="world"
v.overlay ain=admin98 bin=worldbox out=admin98_oceans op=or

By this I was hoping to get
- a box around the world
- oceans as polygons

Looking at the result, it isn't quite convincing:
http://mpa.itc.it/markus/tmp/admin98_oceans_buggy.png

At the west border there seems to be a boundary reaching 90N
but the north boundary is missing. The polygon fill is rather
strange (maybe not?).

Any idea how to get the oceans as polygons into "admin98"?

Markus