here's the bug report: https://bugs.launchpad.net/inkscape/+bug/187449

you can close the topic.

thank you for the answer, i've posted it in the mailing list.
ted gould told me to fill a bug report too.
i'm doing it right now.

thanks again.

it's the Xmoto level editor.

look at that to see the different possibilities:
http://wiki.xmoto.tuxfamily.org/index.php?title=Inkscape-0.4.0

Xmoto is a gpl game:
http://xmoto.tuxfamily.org/

hye, i'm the inksmoto main developper (xmoto level editor which is an inkscape extension) some times ago, Ted told me that: "What I would recommend for this is add a custom X-moto namespace on the XML file. Inkscape will honor this, and keep it in the file. So something like this: <path d="...