Фрейм

<GroupBox Header="Варіанти" Padding="5">

   <StackPanel>

      <CheckBox x:Name="checkBox1" IsThreeState="True" IsChecked="False" Height="20" Content="Сніданок" />

      <CheckBox x:Name="checkBox2" IsThreeState="True" IsChecked="True" Height="20" Content="Обід" />

      <CheckBox x:Name="checkBox3" IsThreeState="True" IsChecked="{x:Null}" Height="20" Content="Вечеря"/>

      <Button Width="80" Margin="3">Замовити</Button>

   </StackPanel>

</GroupBox>