Controls.TextBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mah="clr-namespace:MahApps.Metro.Controls"
                    xmlns:mahConverters="clr-namespace:MahApps.Metro.Converters">

    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.Shared.xaml" />
    </ResourceDictionary.MergedDictionaries>

    <!--  TextBox Style  -->
    <Style x:Key="MahApps.Styles.TextBox" TargetType="{x:Type TextBox}">
        <Setter Property="Background" Value="{DynamicResource MahApps.Brushes.Control.Background}" />
        <Setter Property="BorderBrush" Value="{DynamicResource MahApps.Brushes.TextBox.Border}" />
        <Setter Property="BorderThickness" Value="1" />
        <Setter Property="CaretBrush" Value="{DynamicResource MahApps.Brushes.ThemeForeground}" />
        <Setter Property="ContextMenu" Value="{DynamicResource MahApps.TextBox.ContextMenu}" />
        <Setter Property="FontFamily" Value="{DynamicResource MahApps.Fonts.Family.Control}" />
        <Setter Property="FontSize" Value="{DynamicResource MahApps.Font.Size.Content}" />
        <Setter Property="Foreground" Value="{DynamicResource MahApps.Brushes.Text}" />
        <Setter Property="MinHeight" Value="26" />
        <Setter Property="Padding" Value="4" />
        <Setter Property="SelectionBrush" Value="{DynamicResource MahApps.Brushes.Highlight}" />
        <!--  change SnapsToDevicePixels to True to view a better border and validation error  -->
        <Setter Property="SnapsToDevicePixels" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <Grid>
                        <Border x:Name="Base"
                                Background="{TemplateBinding Background}"
                                BorderBrush="{TemplateBinding BorderBrush}"
                                BorderThickness="{TemplateBinding BorderThickness}"
                                CornerRadius="{TemplateBinding mah:ControlsHelper.CornerRadius}"
                                SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />

                        <Grid x:Name="PART_InnerGrid" Margin="{TemplateBinding BorderThickness}">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition x:Name="TextColumn" Width="*" />
                                <ColumnDefinition x:Name="ButtonColumn" Width="Auto" />
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto" />
                                <RowDefinition x:Name="ButtonRow" Height="*" />
                            </Grid.RowDefinitions>

                            <ScrollViewer x:Name="PART_ContentHost"
                                          Grid.Row="1"
                                          Grid.Column="0"
                                          Margin="0"
                                          Padding="{TemplateBinding Padding}"
                                          VerticalAlignment="Stretch"
                                          Background="{x:Null}"
                                          BorderThickness="0"
                                          IsTabStop="False"
                                          SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                          Style="{DynamicResource MahApps.Styles.ScrollViewer.TextControlContentHost}" />

                            <TextBlock x:Name="PART_Message"
                                       Grid.Row="1"
                                       Grid.Column="0"
                                       Margin="4 0"
                                       Padding="{TemplateBinding Padding}"
                                       HorizontalAlignment="Stretch"
                                       VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                       Foreground="{TemplateBinding Foreground}"
                                       Style="{DynamicResource MahApps.Styles.TextBlock.Watermark}"
                                       Text="{TemplateBinding mah:TextBoxHelper.Watermark}"
                                       TextAlignment="{TemplateBinding mah:TextBoxHelper.WatermarkAlignment}"
                                       TextTrimming="{TemplateBinding mah:TextBoxHelper.WatermarkTrimming}"
                                       TextWrapping="{TemplateBinding mah:TextBoxHelper.WatermarkWrapping}"
                                       Visibility="Collapsed" />

                            <ContentControl x:Name="PART_FloatingMessageContainer"
                                            Grid.Row="0"
                                            Grid.Column="0"
                                            Margin="4 0"
                                            Style="{DynamicResource MahApps.Styles.ContentControl.FloatingMessageContainer}">
                                <ContentControl.Height>
                                    <MultiBinding Converter="{mahConverters:MathMultiplyConverter}" FallbackValue="0">
                                        <Binding ElementName="PART_FloatingMessage"
                                                 Mode="OneWay"
                                                 Path="ActualHeight" />
                                        <Binding ElementName="PART_FloatingMessageContainer"
                                                 Mode="OneWay"
                                                 Path="Opacity" />
                                    </MultiBinding>
                                </ContentControl.Height>
                                <TextBlock x:Name="PART_FloatingMessage"
                                           HorizontalAlignment="Stretch"
                                           VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                           Foreground="{TemplateBinding Foreground}"
                                           Style="{DynamicResource MahApps.Styles.TextBlock.AutoCollapsing}"
                                           Text="{TemplateBinding mah:TextBoxHelper.Watermark}"
                                           TextAlignment="{TemplateBinding mah:TextBoxHelper.WatermarkAlignment}"
                                           TextTrimming="{TemplateBinding mah:TextBoxHelper.WatermarkTrimming}">
                                    <TextBlock.RenderTransform>
                                        <TranslateTransform x:Name="FloatingMessageTransform">
                                            <TranslateTransform.Y>
                                                <MultiBinding Converter="{mahConverters:MathSubtractConverter}" FallbackValue="0">
                                                    <Binding ElementName="PART_FloatingMessage"
                                                             Mode="OneWay"
                                                             Path="ActualHeight" />
                                                    <Binding ElementName="PART_FloatingMessageContainer"
                                                             Mode="OneWay"
                                                             Path="ActualHeight" />
                                                </MultiBinding>
                                            </TranslateTransform.Y>
                                        </TranslateTransform>
                                    </TextBlock.RenderTransform>
                                </TextBlock>
                            </ContentControl>

                            <Button x:Name="PART_ClearText"
                                    Grid.Row="0"
                                    Grid.RowSpan="2"
                                    Grid.Column="1"
                                    Width="{TemplateBinding mah:TextBoxHelper.ButtonWidth}"
                                    Command="{TemplateBinding mah:TextBoxHelper.ButtonCommand}"
                                    CommandParameter="{TemplateBinding mah:TextBoxHelper.ButtonCommandParameter}"
                                    CommandTarget="{TemplateBinding mah:TextBoxHelper.ButtonCommandTarget}"
                                    Content="{TemplateBinding mah:TextBoxHelper.ButtonContent}"
                                    ContentTemplate="{TemplateBinding mah:TextBoxHelper.ButtonContentTemplate}"
                                    Focusable="False"
                                    FontFamily="{TemplateBinding mah:TextBoxHelper.ButtonFontFamily}"
                                    FontSize="{TemplateBinding mah:TextBoxHelper.ButtonFontSize}"
                                    IsTabStop="False"
                                    Style="{DynamicResource MahApps.Styles.Button.Chromeless}"
                                    Template="{TemplateBinding mah:TextBoxHelper.ButtonTemplate}"
                                    Visibility="Visible" />
                        </Grid>

                        <Border x:Name="DisabledVisualElement"
                                Background="{DynamicResource MahApps.Brushes.Control.Disabled}"
                                BorderBrush="{DynamicResource MahApps.Brushes.Control.Disabled}"
                                BorderThickness="{TemplateBinding BorderThickness}"
                                CornerRadius="{TemplateBinding mah:ControlsHelper.CornerRadius}"
                                IsHitTestVisible="False"
                                Opacity="0"
                                SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                                Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(mah:ControlsHelper.DisabledVisualElementVisibility), Mode=OneWay}" />
                    </Grid>
                    <ControlTemplate.Triggers>
                        <Trigger Property="mah:TextBoxHelper.ClearTextButton" Value="True">
                            <Setter TargetName="PART_ClearText" Property="Command" Value="{x:Static mah:MahAppsCommands.ClearControlCommand}" />
                        </Trigger>
                        <MultiTrigger>
                            <MultiTrigger.Conditions>
                                <Condition Property="mah:TextBoxHelper.ClearTextButton" Value="False" />
                                <Condition Property="mah:TextBoxHelper.ButtonCommand" Value="{x:Null}" />
                            </MultiTrigger.Conditions>
                            <Setter TargetName="PART_ClearText" Property="Visibility" Value="Collapsed" />
                        </MultiTrigger>

                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=(mah:TextBoxHelper.ButtonsAlignment)}" Value="Left">
                            <Setter TargetName="ButtonColumn" Property="Width" Value="*" />
                            <Setter TargetName="PART_ClearText" Property="Grid.Column" Value="0" />
                            <Setter TargetName="PART_ContentHost" Property="Grid.Column" Value="1" />
                            <Setter TargetName="PART_FloatingMessageContainer" Property="Grid.Column" Value="1" />
                            <Setter TargetName="PART_Message" Property="Grid.Column" Value="1" />
                            <Setter TargetName="TextColumn" Property="Width" Value="Auto" />
                        </DataTrigger>

                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Text}" Value="">
                            <Setter TargetName="PART_Message" Property="Visibility" Value="Visible" />
                        </DataTrigger>

                        <MultiDataTrigger>
                            <MultiDataTrigger.Conditions>
                                <Condition Binding="{Binding Path=IsVisible, RelativeSource={RelativeSource Self}}" Value="True" />
                                <Condition Binding="{Binding Path=(mah:TextBoxHelper.UseFloatingWatermark), RelativeSource={RelativeSource Self}}" Value="True" />
                                <Condition Binding="{Binding Path=(mah:TextBoxHelper.HasText), RelativeSource={RelativeSource Self}}" Value="True" />
                                <Condition Binding="{Binding Path=(mah:TextBoxHelper.Watermark), RelativeSource={RelativeSource Self}, Converter={x:Static mahConverters:StringIsNullOrEmptyConverter.Default}}" Value="False" />
                            </MultiDataTrigger.Conditions>
                            <MultiDataTrigger.EnterActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.ShowFloatingMessage}" />
                            </MultiDataTrigger.EnterActions>
                            <MultiDataTrigger.ExitActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.HideFloatingMessage}" />
                            </MultiDataTrigger.ExitActions>
                        </MultiDataTrigger>

                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter TargetName="Base" Property="BorderBrush" Value="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(mah:ControlsHelper.MouseOverBorderBrush)}" />
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="False">
                            <Setter TargetName="DisabledVisualElement" Property="Opacity" Value="0.6" />
                        </Trigger>
                        <Trigger Property="IsFocused" Value="True">
                            <Setter TargetName="Base" Property="BorderBrush" Value="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(mah:ControlsHelper.FocusBorderBrush)}" />
                            <Setter TargetName="PART_FloatingMessage" Property="Foreground" Value="{DynamicResource MahApps.Brushes.TextBlock.FloatingMessage}" />
                            <Setter TargetName="PART_FloatingMessage" Property="Opacity" Value="1" />
                        </Trigger>

                        <Trigger SourceName="PART_ClearText" Property="IsMouseOver" Value="True">
                            <Setter TargetName="PART_ClearText" Property="Background" Value="{DynamicResource MahApps.Brushes.Gray8}" />
                            <Setter TargetName="PART_ClearText" Property="Foreground" Value="{DynamicResource MahApps.Brushes.Accent}" />
                        </Trigger>
                        <Trigger SourceName="PART_ClearText" Property="IsPressed" Value="True">
                            <Setter TargetName="PART_ClearText" Property="Background" Value="{DynamicResource MahApps.Brushes.ThemeForeground}" />
                            <Setter TargetName="PART_ClearText" Property="Foreground" Value="{DynamicResource MahApps.Brushes.ThemeBackground}" />
                        </Trigger>

                        <MultiTrigger>
                            <MultiTrigger.Conditions>
                                <Condition Property="mah:TextBoxHelper.HasText" Value="False" />
                                <Condition Property="IsFocused" Value="True" />
                            </MultiTrigger.Conditions>
                            <MultiTrigger.EnterActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.EnterGotFocus}" />
                            </MultiTrigger.EnterActions>
                            <MultiTrigger.ExitActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.ExitGotFocus}" />
                            </MultiTrigger.ExitActions>
                        </MultiTrigger>

                        <Trigger Property="mah:TextBoxHelper.HasText" Value="True">
                            <Trigger.EnterActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.EnterHasText}" />
                            </Trigger.EnterActions>
                            <Trigger.ExitActions>
                                <BeginStoryboard Storyboard="{StaticResource MahApps.Storyboard.ExitHasText}" />
                            </Trigger.ExitActions>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Validation.ErrorTemplate" Value="{DynamicResource MahApps.Templates.ValidationError}" />

        <Setter Property="mah:ControlsHelper.FocusBorderBrush" Value="{DynamicResource MahApps.Brushes.TextBox.Border.Focus}" />
        <Setter Property="mah:ControlsHelper.MouseOverBorderBrush" Value="{DynamicResource MahApps.Brushes.TextBox.Border.MouseOver}" />

        <Setter Property="mah:TextBoxHelper.ButtonCommandParameter" Value="{Binding RelativeSource={RelativeSource Self}, Mode=OneWay}" />
        <Setter Property="mah:TextBoxHelper.ButtonCommandTarget" Value="{Binding RelativeSource={RelativeSource Self}, Mode=OneWay}" />
        <Setter Property="mah:TextBoxHelper.ButtonFontSize" Value="{DynamicResource MahApps.Font.Size.Button.ClearText}" />
        <Setter Property="mah:TextBoxHelper.ButtonTemplate" Value="{DynamicResource MahApps.Templates.Button.Chromeless}" />
        <Setter Property="mah:TextBoxHelper.ButtonWidth" Value="22" />
        <Setter Property="mah:TextBoxHelper.IsMonitoring" Value="True" />
        <Setter Property="mah:TextBoxHelper.IsSpellCheckContextMenuEnabled" Value="{Binding RelativeSource={RelativeSource Self}, Path=(SpellCheck.IsEnabled)}" />
        <Setter Property="mah:TextBoxHelper.WatermarkWrapping" Value="{Binding RelativeSource={RelativeSource Self}, Path=TextWrapping, Mode=OneWay}" />
    </Style>

    <Style x:Key="MahApps.Styles.TextBox.Search"
           BasedOn="{StaticResource MahApps.Styles.TextBox}"
           TargetType="{x:Type TextBox}">
        <!--  Modern - Magnify  -->
        <Setter Property="mah:TextBoxHelper.ButtonCommand" Value="{x:Static mah:MahAppsCommands.SearchCommand}" />
        <Setter Property="mah:TextBoxHelper.ButtonContent" Value="M 42.5,22C 49.4036,22 55,27.5964 55,34.5C 55,41.4036 49.4036,47 42.5,47C 40.1356,47 37.9245,46.3435 36,45.2426L 26.9749,54.2678C 25.8033,55.4393 23.9038,55.4393 22.7322,54.2678C 21.5607,53.0962 21.5607,51.1967 22.7322,50.0251L 31.7971,40.961C 30.6565,39.0755 30,36.8644 30,34.5C 30,27.5964 35.5964,22 42.5,22 Z M 42.5,26C 37.8056,26 34,29.8056 34,34.5C 34,39.1944 37.8056,43 42.5,43C 47.1944,43 51,39.1944 51,34.5C 51,29.8056 47.1944,26 42.5,26 Z" />
        <Setter Property="mah:TextBoxHelper.ButtonContentTemplate">
            <Setter.Value>
                <DataTemplate>
                    <mah:PathIcon Width="{Binding RelativeSource={RelativeSource AncestorType=TextBox}, Path=(mah:TextBoxHelper.ButtonWidth), Mode=OneWay}"
                                  Height="{Binding RelativeSource={RelativeSource AncestorType=TextBox}, Path=(mah:TextBoxHelper.ButtonWidth), Mode=OneWay}"
                                  Padding="3"
                                  Data="{Binding Mode=OneWay}" />
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>