Just when I thought I'd get everything working (again) Gnome has hit me with yet another annoyance.

At least it's relatively simple - From System->Appearance, no matter what control theme I choose, the colours remain exactly the same drab grey. The only actual difference made is when I choose one that changes the style of the controls (Combo/Checkbox, and so on) and even then it's only those affected.
I've tried reinstalling each of the gtk-engines packages I have installed, to no avail. I've tried removing the gtk-engines-qt and qtcurve, which I used because there were some qt styles I liked that worked in Gnome through them. All this did was make Appearance start up slightly quicker.

This is in Debian Squeeze, updated as of this morning.
Now I'm going to go find a cup of tea, and see if I can regain some sanity.

And that's why I don't like tightly-integrated desktop environments. All those connections between programs to worry about!

Maybe there is some section which lets you choose the color (I think it existed in GNOME)?

There is, but it doesn't appear to work - at least not normally.
If I select a colour, sometimes it applies it and the rest of the colour scheme, but most of the time it instead applies something similar to the same drab grey as the default.