No more changes that I have immediately planned. I'm not clinging to any of the work I've done, so if you feel like improving them, please go ahead!
I'm totally aware that doing stuff in pixels is somewhat 1998 in terms of UI design, but I can't think of any other way to restrict the sizes. Same for the spin buttons, which look different on every system. I can see why some of the larger projects don't bother with cross-UI frameworks and just do their entire UI on their own in openGL, like Blender or Lightwave. Overall I'm fine with #ifdefs, let's hope we don't need dozens of them.
Didn't spend much time on the buttons, just wanted to get something going. I can upload the small photoshop file I've used to create the arrows, if needed. I'm pretty sure the grey background is in a separate layer. It'd be nice if the whole icon set of DarkRadiant underwent a full revamp, revisiting every icon, such that style, colours, contrast are consistent, keeping dark and light UI mode in mind. At the moment it has a bit of a Frankenstein touch.