Hi,
regarding "d.vect render=l", I have noticed some weirdness and done some
comparitive eyeball tests on the output:
http://bambi.otago.ac.nz/hamish/grass/bugs/d.vect/
Conclusions:
* polylines (l,d,r) are not crisp
* clipping is wanted in a xmon with white-band out-of-region edge areas
* "l" clipping (culling) leaves mixed out-of-region artifacts
* "c" is off-by-one pixel at edges
Hamish