Avalonia/samples/ControlCatalog/Pages/TabbedPage/TabbedPageEventsPage.xaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="ControlCatalog.Pages.TabbedPageEventsPage">
  <DockPanel>
    <ScrollViewer DockPanel.Dock="Right" Width="260">
      <StackPanel Margin="12" Spacing="8">
        <TextBlock Text="Configuration" FontWeight="SemiBold" FontSize="16"
                   Foreground="{DynamicResource SystemControlHighlightAccentBrush}" />

        <TextBlock Text="Actions" FontWeight="SemiBold" FontSize="13" />
        <Button Content="Select Next Tab" HorizontalAlignment="Stretch" Click="OnSelectNext" />
        <Button Content="Select Previous Tab" HorizontalAlignment="Stretch" Click="OnSelectPrevious" />

        <Separator />

        <DockPanel>
          <TextBlock DockPanel.Dock="Left" Text="Event Log" FontWeight="SemiBold" FontSize="13"
                     VerticalAlignment="Center" />
          <Button DockPanel.Dock="Right" Content="Clear" Click="OnClearLog"
                  HorizontalAlignment="Right" Padding="8,2" FontSize="11" />
        </DockPanel>
        <Border Background="{DynamicResource SystemControlBackgroundBaseLowBrush}"
                CornerRadius="4" Padding="8" MinHeight="120" MaxHeight="300">
          <ScrollViewer x:Name="LogScrollViewer" VerticalScrollBarVisibility="Auto">
            <TextBlock x:Name="EventLog"
                       Text=""
                       FontFamily="Cascadia Code,Consolas,Menlo,monospace"
                       FontSize="11"
                       TextWrapping="Wrap" />
          </ScrollViewer>
        </Border>

        <Separator />

        <TextBlock TextWrapping="Wrap" FontSize="12" Opacity="0.7"
                   Text="SelectionChanged fires when the selected tab changes. NavigatedTo/NavigatedFrom are page lifecycle events that fire on the outgoing and incoming pages." />
      </StackPanel>
    </ScrollViewer>

    <Border DockPanel.Dock="Right" Width="1" Background="{DynamicResource SystemControlForegroundBaseMediumLowBrush}" />

    <Border Margin="12"
            BorderBrush="{DynamicResource SystemControlForegroundBaseMediumLowBrush}"
            BorderThickness="1"
            CornerRadius="6"
            ClipToBounds="True">
      <!-- Pages configured in code-behind so lifecycle events are subscribed before NavigatedTo fires. -->
      <TabbedPage x:Name="DemoTabs" TabPlacement="Bottom" />
    </Border>
  </DockPanel>
</UserControl>