BuildProcess/WpfControlLibrary/IpAddress/IpAddressControl.xaml

<UserControl x:Class="WpfControlLibrary.IpAddress.IpAddressControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:local="clr-namespace:WpfControlLibrary.IpAddress"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             Margin="10,0"
             d:DesignHeight="50"
             d:DesignWidth="800"
             mc:Ignorable="d"
             Background="White">
    <UserControl.Resources>
        <ControlTemplate x:Key="validationTemplate">
            <DockPanel>
                <TextBlock Margin="1,2"
                           DockPanel.Dock="Right"
                           FontSize="{DynamicResource ResourceKey=Heading4}"
                           FontWeight="Bold"
                           Foreground="Red"
                           Text="" />
                <AdornedElementPlaceholder />
            </DockPanel>
        </ControlTemplate>
        <Style x:Key="CustomTextBoxTextStyle"
               TargetType="TextBox">
            <Setter Property="MaxLength"
                    Value="3" />
            <Setter Property="HorizontalAlignment"
                    Value="Stretch" />
            <Setter Property="VerticalAlignment"
                    Value="Center" />
            <Style.Triggers>
                <Trigger Property="Validation.HasError"
                         Value="True">
                    <Trigger.Setters>
                        <Setter Property="ToolTip"
                                Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" />
                        <Setter Property="BorderBrush"
                                Value="Red" />
                        <Setter Property="Background"
                                Value="Red" />
                    </Trigger.Setters>
                </Trigger>
            </Style.Triggers>
        </Style>
    </UserControl.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition MinWidth="30" />
            <ColumnDefinition Width="10" />
            <ColumnDefinition MinWidth="30" />
            <ColumnDefinition Width="10" />
            <ColumnDefinition MinWidth="30" />
            <ColumnDefinition Width="10" />
            <ColumnDefinition MinWidth="30" />
        </Grid.ColumnDefinitions>

        <!--  Part 1  -->
        <TextBox Grid.Column="0"
                 BorderThickness="0"
                 HorizontalAlignment="Stretch"
                 VerticalAlignment="Stretch"
                 VerticalContentAlignment="Center"
                 HorizontalContentAlignment="Center"
                 x:Name="part1"
                 PreviewKeyDown="Part1_PreviewKeyDown"
                 local:FocusChangeExtension.IsFocused="{Binding IsPart1Focused, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}"
                 Style="{StaticResource CustomTextBoxTextStyle}"
                 Validation.ErrorTemplate="{StaticResource validationTemplate}">
            <TextBox.Text>
                <Binding Path="Part1"
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <local:IPRangeValidationRule Max="255"
                                                     Min="0" />
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
        <TextBlock Grid.Column="1"
                   HorizontalAlignment="Center"
                   FontSize="15"
                   Text="."
                   VerticalAlignment="Center" />

        <!--  Part 2  -->
        <TextBox Grid.Column="2"
                 x:Name="part2"
                 BorderThickness="0"
                 VerticalAlignment="Stretch"
                 VerticalContentAlignment="Center"
                 HorizontalContentAlignment="Center"
                 PreviewKeyDown="Part2_KeyDown"
                 local:FocusChangeExtension.IsFocused="{Binding IsPart2Focused}"
                 Style="{StaticResource CustomTextBoxTextStyle}"
                 Validation.ErrorTemplate="{StaticResource validationTemplate}">
            <TextBox.Text>
                <Binding Path="Part2"
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <local:IPRangeValidationRule Max="255"
                                                     Min="0" />
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
        <TextBlock Grid.Column="3"
                   HorizontalAlignment="Center"
                   FontSize="15"
                   Text="."
                   VerticalAlignment="Center" />

        <!--  Part 3  -->
        <TextBox Grid.Column="4"
                 x:Name="part3"
                 BorderThickness="0"
                 VerticalAlignment="Stretch"
                 VerticalContentAlignment="Center"
                 HorizontalContentAlignment="Center"
                 PreviewKeyDown="Part3_KeyDown"
                 local:FocusChangeExtension.IsFocused="{Binding IsPart3Focused}"
                 Style="{StaticResource CustomTextBoxTextStyle}"
                 Validation.ErrorTemplate="{StaticResource validationTemplate}">
            <TextBox.Text>
                <Binding Path="Part3"
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <local:IPRangeValidationRule Max="255"
                                                     Min="0" />
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
        <TextBlock Grid.Column="5"
                   HorizontalAlignment="Center"
                   FontSize="15"
                   Text="."
                   VerticalAlignment="Center" />

        <!--  Part 4  -->
        <TextBox Grid.Column="6"
                 x:Name="part4"
                 BorderThickness="0"
                 VerticalAlignment="Stretch"
                 VerticalContentAlignment="Center"
                 HorizontalContentAlignment="Center"
                 PreviewKeyDown="Part4_KeyDown"
                 local:FocusChangeExtension.IsFocused="{Binding IsPart4Focused}"
                 Style="{StaticResource CustomTextBoxTextStyle}"
                 Validation.ErrorTemplate="{StaticResource validationTemplate}">
            <TextBox.Text>
                <Binding Path="Part4"
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <local:IPRangeValidationRule Max="255"
                                                     Min="0" />
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
    </Grid>
</UserControl>