add FocusVisualStyle for some controls

src/Shared/HandyControl_Shared/Themes/Styles/CalendarWithClock.xaml

@@ -9,7 +9,7 @@
     </ResourceDictionary.MergedDictionaries>
 
     <Style TargetType="controls:CalendarWithClock">
-        <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
+        <Setter Property="Focusable" Value="False"/>
         <Setter Property="Foreground" Value="{DynamicResource PrimaryTextBrush}"/>
         <Setter Property="Background" Value="{DynamicResource RegionBrush}"/>
         <Setter Property="BorderBrush" Value="{DynamicResource BorderBrush}"/>