For those playing with the newly released Avalon CTP and Chris Anderson's XamlPad application, and are using other Visual Styles than Windows XP (TGTSoft's StyleXP or patched UXTheme.dll), you can follow these instructions:

• Go in folder "C:\WINDOWS\Resources\Themes\Luna"
• Copy file "PresentationFramework.Luna.NormalColor.FxStyles"
• Go back one folder, then into your current theme's folder
• Paste the copied file
• Rename the file as follows:
• Replace "Luna" with the name of the "msstyles" file
• Replace "NormalColor" with the name of the folder under "Shell" which matches the active color scheme.

For example, I'm running with the CodeOpus theme with the Dusk color scheme:

Within "C:\WINDOWS\Resources\Themes", I copied "Luna\PresentationFramework.Luna.NormalColor.FxStyles" to "CodeOpus\PresentationFramework.CodeOpus.Dusk22.FxStyles". Notice that the color scheme part matches the subfolder name, not the color scheme name ("CodeOpus\Shell\Dusk22" in my case).

BTW, XamlPad's ClickOnce does not work within FireFox. Simply launch it from IE.