[Inkscape-devel] Effect that modifies the document properties?

Hello. I'm trying to write an Effect extension that will allow the creation of cover templates for perfect bound books, which involves changing the document properties and adding guides lines to the current document. I have a Ruby script and an .inx file set up correctly, and when I examine the XML output from the script, the SVG that is returned is correct. When this file is written back to stdout at the end of the script, no changes occur within Inkscape. Can Effects modify the document properties and, if they can't, would it be a good idea to add a new type of extension that could?

Thanks,

John