#919 – Changing the Border of a TextBox

You can change the border displayed around a TextBox using the BorderBrush and BorderThickness properties.

In the example below, we use a trigger to change the border of the TextBox that has focus.

    <Window.Resources>
        <Style TargetType="{x:Type TextBox}">
            <Setter Property="Template">
                <Setter.Value>
                    <!-- Modify default template, to change triggers -->
                    <ControlTemplate TargetType="{x:Type TextBoxBase}">
                        <Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
                            <ScrollViewer x:Name="PART_ContentHost" Focusable="False" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsEnabled" Value="False">
                                <Setter Property="Opacity" TargetName="border" Value="0.56"/>
                            </Trigger>
                            <!-- Original triggers -->
                            <!--<Trigger Property="IsMouseOver" Value="True">
                                <Setter Property="BorderBrush" TargetName="border" Value="#FF7EB4EA"/>
                            </Trigger>
                            <Trigger Property="IsKeyboardFocused" Value="True">
                                <Setter Property="BorderBrush" TargetName="border" Value="#FF569DE5"/>
                            </Trigger>-->
                            <!-- MY trigger -->
                            <Trigger Property="IsFocused" Value="True">
                                <Setter Property="BorderBrush" Value="Green"/>
                                <Setter Property="BorderThickness" Value="2"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>

    <Grid Margin="5">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <Label Content="Your hobo name:"/>
        <TextBox
            Grid.Column="1" Height="25"
            Margin="5"/>
        <Label Grid.Row="1" Content="Favorite cheese:" />
        <TextBox
            Grid.Row="1" Grid.Column="1" Height="25"
            Margin="5"/>
    </Grid>