[Scribus] transparency question

[jrm at kw.igs.net]

Hi,

This regards using png images with portions that are
100% transparent.  What seems to happen is that this
kind of transparency is respected even when exporting
to PDF 1.3 (as seen in acroread and kpdf), which is not
what I was expecting.  So I'm wondering if this is
too good to be true, that I may be able to use this
kind of transparency without restriction on what PDF
version to use, maybe even PDF/X-3...  The question is, 
can I rely on this behaviour?

What I guess was expecting was that since "PDF 1.3 does
not allow transparency" the transparent part of the png
would be made white, or maybe black.

Regards,
John (MacPhail)