Hi,
I'm pleased to see the custom theme option, but there are some inconsistencies in how the colors are applied that really should be corrected. It's easiest to explain with a screenshot:
Basically, the Edit/Close/Assign/Actions/Reply buttons are drawn with black text on a solid color when it would likely make more sense to match them to the top tabs, both in terms of having a gradient background and also having a customizable text color. This would work better in cases like ours, where the desired coloring is rather dark. Also, as shown with the "Actions" tab, the rollover color does not follow the custom theme settings and stays as the default blue color.
It would also be nice to be able to customize the light blue background (May 28 portion of the screenshot).
Thanks