The Telerik themes are designed to work mainly with our RadControls and only some of the native WPF/Silverlight controls.
Telerik themes can be applied to the following native WPF controls:
When you set an application theme, it will be applied to all Telerik controls and to the native controls listed above. You may send us a small application in a new support ticket where we can see why this theme is applied only to RadGridView, thus we will be able to provide you with an appropriate solution. On a side note we ship our themes as a separate projects from where you can get the styles for our controls, you may find these in the Themes folder of your personal installation. Furthermore with our Q1 release you may get the xaml files for Office_Black theme, please find attached this folder.
the Telerik team