I combined few white icon uncomplete inkscape themes which I found on the internet. This is the outcome. I tested it only under OSX. For the toolbar I used New Improved Inkscape Tool Icons from here: http://gnome-look.org/content/show.php/New+Improved+Inkscape+Tool+Icons?content=155138
Under OSX: Place the file icons.svg into /Applications/Inkscape.app/Contents/Resources/Icons
Use with dark gtk theme.