Thank you for the kind words Bryce. We now have two sets of tool icons and there are arguments in favor of using either. If consistency across application is preferred, the art libre set is still there to be used. I do think the Art Libre calligraphy icon was a wrong choice, as Gimp has a similar tool called "ink" with its own icon of an inkwell, and that should have been used for the calligraphy tool instead. As for the 3Dbox (contributed by dphase, by the way), tango guidelines call for a specific frontal perspective so this icon will blend better into the theme.
We still need to bear in mind that the theme is supposed to work on a dark background as well, and I'm afraid in wanting to make them more distinct on a light background I failed at that. I tried to create tango-compliant icons with dark strokes instead of the white line with darker stroke around it but was not happy with the result. So - if anyone can produce a nice looking set of icons using dark strokes I'd be happy to see it.
I will leave it to you developers to decide which icons to use. Any small change to icons (e.g., making the circle icon look flatter or coloring the box) can be made by Jiho or anyone else easily. By the way, is there any way of creating said oxes in any color other than blue?
Michael