Fixing invalid operation exception when tabbing out of MaterialDesignTabRadioButton (#1072)

Author: Keboo

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.RadioButton.xaml

@@ -218,7 +218,7 @@
     </Style>
 
     <Style x:Key="MaterialDesignTabRadioButton"  TargetType="{x:Type RadioButton}">
-        <Setter Property="FocusVisualStyle" Value="{StaticResource MaterialDesignFocusVisual}"/>
+        <Setter Property="FocusVisualStyle" Value="{StaticResource FocusVisual}"/>
         <Setter Property="Foreground" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type FrameworkElement}}, Path=(TextElement.Foreground)}"/>
         <Setter Property="Background" Value="Transparent"/>
         <Setter Property="BorderBrush" Value="{DynamicResource SecondaryAccentBrush}"/>