Dear All,
Thank you very much for your question and I am very sorry about the issue!
Unfortunately, this is a known limitation of Archicad. In 3D, each construction element will have contour lines, and these lines cannot be transparent. The only workaround I can think of is matching the pen color with the window/door surface to make them less pronounced in 3D.
Once again I am very sorry for the inconvenience! Please let me know if you have any further questions!
Best regards,
Minh
Minh Nguyen
Technical Support Engineer
GRAPHISOFT