This Style is not applied when Windows8 Theme is set for the GridView (only) - it works if an ApplicationTheme is set. <telerik:RadGridView telerik:StyleManager.Theme="Windows8" Name="clubsGrid" .../> <Style TargetType="telerik:GroupHeaderRow" telerik:StyleManager.BasedOn="Windows8"> <Setter Property="ShowGroupHeaderColumnAggregates" Value="True" /> <Setter Property="Background" Value="Red"/> </Style>
When we are working with StyleManager and the theme is set to element, the implicit styles should not be applied. RadGridView has an internal logic that will override the implicit styles, defined above. If you need to set the theme on RadGridView and to use implicit styles, you should use the GroupRowStyle, instead.