Use StyleManager to Apply Theme on MS Controls
The Telerik themes are designed to work mainly with our controls and some native WPF controls. Our theming mechanism cannot cover the full control list included in WPF.
Native controls supported by the Telerik theming mechanism
Below is the full control list of native WPF controls supported by the Telerik theming mechanism:
System.Windows.Controls.Button
System.Windows.Controls.ScrollViewer
System.Windows.Controls.CheckBox
System.Windows.Controls.TextBox
System.Windows.Controls.RadioButton
System.Windows.Controls.ListBox
System.Windows.Controls.PasswordBox
System.Windows.Controls.Primitives.RepeatButton
System.Windows.Controls.Tooltip
System.Windows.Documents.Hyperlink
System.Windows.Controls.Primitives.StatusBar
System.Windows.Controls.GridSplitter
System.Windows.Controls.Separator
For all of those controls you may specify the theme for them as you may for any Telerik control.
When you apply an Application theme at runtime, though, only Telerik controls will be styled - not the native ones supported by our theming mechanism. If you want to style those native controls based on the current application theme, you should manually set the corresponding theme. For example, the code for a Button would be like so:
<Window.Resources>
<telerik:Expression_DarkTheme x:Key="Theme" />
<Style TargetType="Button">
<Setter Property="telerik:StyleManager.Theme" Value="{StaticResource Theme}"/>
</Style>
</Window.Resources>