waterMarkTextBox

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

                    xmlns:local="clr-namespace:MyWPFCustomControls"

                    >

    <Style  TargetType="{x:Type local:WaterMarkTextBox}">

        <Setter Property="Background" Value="#ffffff"/>

        <Setter Property="VerticalContentAlignment" Value="Center" />

        <Setter Property="BorderBrush" Value="#5d7fad"></Setter>

        <Setter Property="FontWeight" Value="Normal"></Setter>

        <Setter Property="Foreground" Value="#0c223a"></Setter>

        <Setter Property="Padding" Value="5,0,5,2"></Setter>

        <Setter Property="Margin" Value=""/>

        <Setter Property="FontSize" Value=""></Setter>

        <Setter Property="FontFamily" Value="Arial"></Setter>

        <Setter Property="FlowDirection" Value="LeftToRight"></Setter>

        <Setter Property="Template" >

            <Setter.Value>

                <ControlTemplate TargetType="{x:Type local:WaterMarkTextBox}" >

                    <Border Background="{TemplateBinding Background}" x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="">

                        <Grid>

                            <ScrollViewer   x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />

                            <ContentPresenter x:Name="PART_WatermarkHost"  Content="{TemplateBinding Watermark}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" IsHitTestVisible="False" Margin="{TemplateBinding Padding}" Visibility="Collapsed" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">

                                <ContentPresenter.ContentTemplate>

                                    <DataTemplate>

                                        <ContentControl Content="{Binding}" Foreground="Gray" Focusable="False"/>

                                    </DataTemplate>

                                </ContentPresenter.ContentTemplate>

                            </ContentPresenter>

                        </Grid>

                    </Border>

                    <ControlTemplate.Triggers>

                        <MultiTrigger>

                            <MultiTrigger.Conditions>

                                <Condition Property="IsFocused" Value="False"/>

                                <Condition Property="Text" Value=""/>

                            </MultiTrigger.Conditions>

                            <Setter Property="Visibility" TargetName="PART_WatermarkHost" Value="Visible"/>

                        </MultiTrigger>

                        <Trigger Property="IsEnabled" Value="False">

                            <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" TargetName="Bd"/>

                            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>

                        </Trigger>

                        <Trigger Property="IsFocused" Value="True" >

                            <Setter TargetName="Bd" Property="Effect">

                                <Setter.Value>

                                    <DropShadowEffect ShadowDepth="" BlurRadius="" Color="#fe1C67C7"></DropShadowEffect>

                                </Setter.Value>

                            </Setter>

                        </Trigger>

                        <Trigger Property="IsMouseOver" Value="True">

                            <Setter TargetName="Bd"  Property="Effect">

                                <Setter.Value>

                                    <DropShadowEffect ShadowDepth="" BlurRadius="" Color="#Fe9DBADF"></DropShadowEffect>

                                </Setter.Value>

                            </Setter>

                        </Trigger>

                        <Trigger Property="Height" Value="Auto">

                            <Setter Property="MinHeight" Value=""/>

                        </Trigger>

                        <Trigger Property="Validation.HasError" Value="True">

                            <Setter TargetName="Bd" Property="BorderBrush" Value="Red"/>

                            <Setter Property="ToolTip">

                                <Setter.Value>

                                    <Binding

                            Path="(Validation.Errors).CurrentItem.ErrorContent"

                            RelativeSource="{x:Static RelativeSource.Self}"

                            />

                                </Setter.Value>

                            </Setter>

                        </Trigger>

                    </ControlTemplate.Triggers>

                </ControlTemplate>

            </Setter.Value>

        </Setter>

        <Setter Property="BorderThickness" Value="">

            <!--<Setter.Value>

                <Thickness Bottom="" Left="" Right="" Top=""></Thickness>

            </Setter.Value>-->

        </Setter>

        <Setter Property="Validation.ErrorTemplate">

            <Setter.Value>

                <ControlTemplate>

                </ControlTemplate>

            </Setter.Value>

        </Setter>

        <Style.Triggers>

            <!--<Trigger Property="Attach:AttachProperty.IsMandatory" Value="True">

                <Setter Property="Background" Value="LightYellow"/>

            </Trigger>-->

            <!--<Trigger Property="IsFocused" Value="True" >

                <Setter Property="Button.Effect">

                    <Setter.Value>

                        <DropShadowEffect ShadowDepth="" BlurRadius="" Color="#fe1C67C7"></DropShadowEffect>

                    </Setter.Value>

                </Setter>

            </Trigger>

            <Trigger Property="IsMouseOver" Value="True">

                <Setter Property="Button.Effect">

                    <Setter.Value>

                        <DropShadowEffect ShadowDepth="" BlurRadius="" Color="#Fe9DBADF"></DropShadowEffect>

                    </Setter.Value>

                </Setter>

            </Trigger>-->

            <!--<Trigger Property="Validation.HasError" Value="True">

                <Setter Property="FontFamily" Value="Arial"/>

                <Setter Property="FontSize" Value=""/>

                <Setter Property="ForceCursor" Value="False"/>

                <Setter Property="Foreground" Value="Gray"/>

                <Setter Property="FontWeight" Value="Normal"/>

                <Setter Property="HorizontalContentAlignment" Value="Left"/>

                <Setter Property="VerticalContentAlignment" Value="Center"/>

                <Setter Property="Padding" Value="5,0,5,2"></Setter>

                <Setter Property="Margin" Value=""/>

                <Setter Property="MinHeight" Value=""/>

                <Setter Property="Template">

                    <Setter.Value>

                        <ControlTemplate TargetType="{x:Type TextBox}">

                                <Border Background="#ffffff" BorderBrush="Red" x:Name="Bd" CornerRadius="" BorderThickness="">

                                    <Grid>

                                        <TextBlock x:Name="PART_MyWaterMarkTextBlock" Visibility="Collapsed" VerticalAlignment="Center" HorizontalAlignment="Left" Padding="5,0,0,3" Foreground="Gray"/>

                                        <ScrollViewer  x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />

                                    </Grid>

                                </Border>

                        </ControlTemplate>

                    </Setter.Value>

                </Setter>

            </Trigger>-->

        </Style.Triggers>

    </Style>

</ResourceDictionary>

xaml

 public  class WaterMarkTextBox:TextBox

    {

        public string Watermark

        {

            get { return (string)GetValue(WatermarkProperty); }

            set { SetValue(WatermarkProperty, value); }

        }

        // Using a DependencyProperty as the backing store for Watermark.  This enables animation, styling, binding, etc...

        public static readonly DependencyProperty WatermarkProperty =

            DependencyProperty.Register("Watermark", typeof(string), typeof(WaterMarkTextBox), new PropertyMetadata(null));

      public WaterMarkTextBox()

      {

      }

    }

cs