I have tested the DF taskbar with all 3 native XP themes, and the MS Zune (downloaded) and MS Royal Blue (MCE 2005) themes. I have also tested with a variety of random XP themes I found on DeviantArt. So far they have all worked reasonably well, with no major graphical glitches. I'd love to hear any reports of any themes working or not working, especially if you're using a hacked theme.

Interesting... DisplayFusion uses the Windows visual styles system to draw itself, it should look the same. Can you post a link to the theme you are using and I'll take a look?