Hi,
If you want to change the theme of the PropertyGrid, you will have to modify 1 of the following files :
-Xceed.Wpf.Toolkit/PropertyGrid/Themes/Aero2.NormalColor.xaml (in Windows8)
-Xceed.Wpf.Toolkit/PropertyGrid/Themes/Generic.xaml (in Windows7)
Then, just using a PropertyGrid should apply these default themes.
If you want to change the theme of the PropertyGrid, you will have to modify 1 of the following files :
-Xceed.Wpf.Toolkit/PropertyGrid/Themes/Aero2.NormalColor.xaml (in Windows8)
-Xceed.Wpf.Toolkit/PropertyGrid/Themes/Generic.xaml (in Windows7)
Then, just using a PropertyGrid should apply these default themes.