TextBox的错误模板

 <Style x:Key="TextBoxValidationStyle" TargetType="{x:Type TextBox}">
        <Setter  Property="Validation.ErrorTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <DockPanel LastChildFill="True">
                        <TextBlock DockPanel.Dock="Right" Foreground="Red" FontSize="14" FontWeight="Bold"
                                       ToolTip="{Binding ElementName=PlaceHolder,Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">*</TextBlock>
                        <Border BorderBrush="Red" BorderThickness="1">
                            <AdornedElementPlaceholder Name="PlaceHolder"></AdornedElementPlaceholder>
                        </Border>
                    </DockPanel>
                </ControlTemplate>

            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
                <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self},Path=(Validation.Errors)[0].ErrorContent}">

                </Setter>
            </Trigger>
        </Style.Triggers>
    </Style>