> IIUC you're asking that we implement the default behavior for CSS3 Paged Media margin boxes:
> Will that do the trick for the pdf.js use cases?
Together with a new callback for printing canvas graphics, this looks very promising.
I'm still a little bit concerned about blocking the UI for printing (esp. for large documents which is common if you print some PDF), the corresponding memory usage and if page preview will scale for large documents.