Support for preview overprinting

[Ale-]

For the final user it would be very useful to preview overprinted elements in the document. When working with many of them, the impossibility of previewing them is prone to errors.
A workaround is to use multiply blend mode until the generation of the PDF. Maybe that workaround is a base for a possible solution using some kind of a 'fake blend mode' that is removed in the pre-press process.

[aoloe]

let's give it a second try: https://bugs.scribus.net/view.php?id=11061
any similarities? : - )

but i think the other ticket is about warning about the usage and your concern about make the effect of overprinting somehow visible on screen?

personally, i try to find some ways to make overprinting "more visible", but i really don't know what's a good idea to solve this issue...