Hi Lagarto,
well, I must have been blind. Thought I used a pen stroke instead of the rectangle... Everything is ok if I use a stroke instead of an rectangle, using a table also does the job. So the problem is solved for me, but maybe not for Serif? The rectangle shows width 0 (could this calue prohibit rendering?), color is pure white and the rectangle isn't appearing inside the PDF, regardless of the stroke width (which should not the case, as long as I can see a line in the Publisher UI, right?).
I will upload files as soon as I'm able to (getting error "7 - Please contact us for assistance", regardless of browser?). Thanks Legarto.
Robert