<Window x:Class="WpfAppExamples.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="RadioButtonSample" Height="150" Width="250"> <Window.Resources> <Style TargetType="RadioButton" BasedOn="{StaticResource {x:Type RadioButton}}"> <Style.Triggers> <Trigger Property="IsChecked" Value="False"> <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/> </Trigger> </Style.Triggers> </Style> </Window.Resources> <StackPanel Margin="10"> <Label FontWeight="Bold">Are you ready?</Label> <RadioButton GroupName="testing">Yes</RadioButton> <RadioButton GroupName="testing">No</RadioButton> <RadioButton IsChecked="True" GroupName="testing">Maybe</RadioButton> </StackPanel> </Window>