I recently upgraded to Luna, and learned of the dark theme, and thought I'd give it a try. It's mostly good, with a few general glitches, and a few CDT specific glitches. In the Java editor the currently focused variable is highlighted appropriately and can easily be read. In CDT, however, the background goes white, and you can't read the identifier at all anymore. The same is true for ifdef blocks which are whited out. In the case of the ifdef block, it'd be nice if it was greyed out, such that it could still be read easily, just obviously not active. In the case of the variable, whatever Java editor is doing works nicely.
I imagine the above are configurable, and I did have a go at fixing it, but failed. Happy to have another go with some direction, however I think the defaults should work, and they very much don't in the dark theme.