Hi Guillermo,
I'd like to know if you considered applying the marks to a selection (using the bbox rectangle as limit) as an option. ... and the author of the "cut marks" extension offers you to join forces and work together.
We (Aurélio and me) are ok to work together and plan to add this option.
Another interesting feature would be using guides as placeholders for fold or die-punch marks.
Looks far more complex... Why not. But probably not in a near future.
About the registration marks discussion, I also find the V shapes too exotic. Generally I only see superposed circles with crosses in C, M, Y and K channels. However, I don't see anything wrong with using both. The circles with crosses on the corners, and the V shapes on the middle. What do you think?
I first wanted to keep it as simple as possible (and close to Scribus behaviour), and I have no plan to add that kind of mark in the corner. Should be a community debate. I finally choose Juca's option and replaced circles by V shapes.
Thanks for your comments. -- Nicolas