Comment 25 for bug 658055

I had the same problem in Kubuntu 10.10. After a few guys have pointed out symlinking here's a very easy command which works around the problem:
 ln -s /usr/share/icons/oxygen/48x48/actions/document-properties.png ~/.config/inkscape/icons/gtk-properties.png
This will just tell inkscape to use the document-properties.png icon as gtk-properties.png, no other settings required (I'm using oxygen with gtk+ qtcurve).