hc:DatePicker support for Validation

src/Shared/HandyControl_Shared/Themes/Styles/Base/DatePickerBaseStyle.xaml

@@ -34,6 +34,7 @@
         <Setter Property="Padding" Value="{StaticResource DefaultInputPadding}"/>
         <Setter Property="BorderThickness" Value="1"/>
         <Setter Property="VerticalContentAlignment" Value="Center"/>
+        <Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="DatePicker">
@@ -343,6 +344,7 @@
     </ControlTemplate>
 
     <Style x:Key="DatePickerPlusBaseStyle" BasedOn="{StaticResource DatePickerExtendBaseStyle}" TargetType="hc:DatePicker">
+        <Setter Property="IsError" Value="{Binding Path=(Validation.HasError),RelativeSource={RelativeSource Self}}"/>
         <Setter Property="CaretBrush" Value="{DynamicResource PrimaryTextBrush}"/>
         <Setter Property="Template" Value="{StaticResource DatePickerPlusTopTemplate}"/>
         <Style.Triggers>