OK, thinking a little more of the problem, there's a way: a) create a layer "Transparent" at the depth of the transparent objects, move transparent objects to this layer ; b) view only this layer and "export bitmap", export the whole page as PNG for easy alignment or a subset if ...

Hi I am now highly satisfied with the PDF export of inkscape, as it seems to use all the possibilities of PDF standard including transparencies. I am using Okular myself to view PDFs, and most of the transparencies I use (transparent fill or gradient) are rendered appropriately. But now, the problem...