I found out, that my desktop breaks when I do the
dpkg-reconfigure locales
once I do it, the LXDE stops working, anyway it's not a big issue

About Inkscape, the biggest issue is that the window does not fit in the desktop, I can't see some icons and the color palette. The Ctr+"." doesn't work for me, I suppose due to the spanish keyboard, so It's difficult to do some things

And one question... would it break easy debian to upgrade it to unstable repositories??

Edit: OK, the Ctr+. thing was pretty easy... I have to press the "ñ" key because there it's where the US keyboard has the dot...