I've just stumbled across your toolbar icons, which I like a lot.
I've tried using some of them, but unfortunately they appear as monochrome, or in several cases a just blank grey square.
I suspect that this might be because I'm using Steven's Spotify B skin? In general, I prefer a darker skin and this one seems close to perfect - though there are a few minor details which I might try tweaking - if/when I get round to experimenting with skins myself.

Do you know whether it is possible to make your buttons appear as designed using this particular skin, or is something in the skin design restricting me to monochrome (for the time being at least)? I'll do some more experiments when I get a moment or two.....
Colour introduced using Highlighting Rules seems to work OK, but I realise that this is not quite the same thing.
Thanks very much for the buttons. I'm sad that it seems I can't use them with my current configuration.