How to make WPF TextBox with a scrollbar automatically scroll to the bottom when lines are added?

You can whenever you add content to that TextBox or when you listen to the event TextChanged fire this method:TextBoxBase.ScrollToEnd().

You could write an attached property or even better a behavior that listens to the TextChanged event and scrolls to the bottom in the callback.

There is a way to do it in XAML, you can use this Style to display it like a Console would (Be aware of the drawbacks, it just looks like a Console but does not completely behave like it)

        <Style x:Key="ConsoleTextBox" TargetType="{x:Type TextBox}">            <Setter Property="IsReadOnly" Value="True"/>            <Setter Property="Template">                <Setter.Value>                    <ControlTemplate TargetType="TextBox">                        <ScrollViewer RenderTransformOrigin="0.5,0.5" VerticalScrollBarVisibility="Auto">                            <ScrollViewer.RenderTransform>                                <ScaleTransform ScaleY="-1"/>                            </ScrollViewer.RenderTransform>                            <TextBox Text="{TemplateBinding Text}" RenderTransformOrigin="0.5,0.5">                                <TextBox.RenderTransform>                                    <ScaleTransform ScaleY="-1"/>                                </TextBox.RenderTransform>                            </TextBox>                        </ScrollViewer>                    </ControlTemplate>                </Setter.Value>            </Setter>        </Style>

How does it work

Inside the TextBox, a ScrollViewer is flipped vertically (the "new" lines are added at the Bottom)

In the ScrollViewer, there is another Textbox which is flipped Vertically to display the Text correctly (not upside down).

Using the Style

Include it in your App.xaml or via ResourceDictionary and set the Style of the TextBox to ConsoleTextBox.

<TextBox Style="{StaticResource ConsoleTextBox}"/>

Drawbacks

• When you copy the Text from this "Console" there will be no Line Breaks.
• Scrolling with the Mouse is inverted