You're right in that not all of the panels displayed in the Options Dialog have smart resizing. Many of them are just individual options forms from previous versions that got sucked into the Options Dialog. Some of them will probably get smarter as we go along and add resizing code. Some of them will probably never have this code added.
Even if you resized the tab control on the Color Coding dialog, you then have the same problem of how to fill up more space with the same number of controls. Maybe the whitespace would look better inside the tab control rather than outside of it, but I think if you made a huge tab control with lots of whitespace inside of it, the Import and Colors buttons would get lost all by themselves at the bottom.
Eh, it's probably six of one, half a dozen of the other...
