Avalonia/samples/TextTestApp/MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TextTestApp"
    x:Class="TextTestApp.MainWindow"
    Title="Text Test App" Width="700" Height="700">

    <DockPanel>
      <Border DockPanel.Dock="Bottom" Background="WhiteSmoke" BorderThickness="0,1,0,0" BorderBrush="Silver" Padding="2">
        <DockPanel>
          <ToggleSwitch Name="_hitRangeToggle" DockPanel.Dock="Right" OnContent="HitTestTextRange" OffContent="HitTestTextPosition" IsCheckedChanged="OnHitTestMethodChanged" />
          <StackPanel Orientation="Horizontal" VerticalAlignment="Center">
            <TextBlock Text="HitTestPoint:" Margin="5,0" />
            <TextBlock Name="_coordinates" MinWidth="120" />
            <Border Width="5" BorderThickness="1,0,0,0" BorderBrush="Silver" UseLayoutRounding="True" Margin="5,0,0,0" />
            <TextBlock Text="TextPosition:" Margin="5,0" />
            <TextBlock Name="_hit" MinWidth="60" />
            <Border Width="5" BorderThickness="1,0,0,0" BorderBrush="Silver" UseLayoutRounding="True" Margin="5,0,0,0" />
          </StackPanel>
        </DockPanel>
      </Border>

      <DockPanel DockPanel.Dock="Top" Margin="5">
        <StackPanel Orientation="Horizontal" DockPanel.Dock="Right">
          <Label Content="_Font:" Target="{Binding ElementName=_font}" VerticalAlignment="Center" Margin="5,0,0,0" />
          <ComboBox Name="_font" ItemsSource="{Binding SystemFonts, Source={x:Static FontManager.Current}}" />
          <Label Content="_Size:" Target="{Binding ElementName=_size}" VerticalAlignment="Center" Margin="5,0,0,0" />
          <TextBox Name="_size" VerticalAlignment="Center" Text="64" />
          <Button VerticalAlignment="Center" Click="OnNewWindowClick" ToolTip.Tip="New window" Margin="5,0,0,0">+</Button>
        </StackPanel>

        <Label Content="_Text:" Target="{Binding ElementName=_text}"  VerticalAlignment="Center"/>
        <TextBox Name="_text" Text="Hello!" VerticalAlignment="Center" />
      </DockPanel>

      <Grid RowDefinitions="*,5,*">
        <local:InteractiveLineControl Name="_rendering" DockPanel.Dock="Top" Margin="16" HorizontalAlignment="Center" 
                                  
                                      Text="{Binding Text, ElementName=_text}"
                                      FontFamily="{Binding SelectedValue, ElementName=_font}"
                                      FontSize="{Binding Text, ElementName=_size}"
                                      Background="BlanchedAlmond"
                                      ExtentStroke="Black"
                                      BaselineStroke="Blue"
                                      TextBoundsStroke="Goldenrod"
                                      RunBoundsStroke="Gold"
                                      NextHitStroke="Green"
                                      PreviousHitStroke="Blue"
                                      BackspaceHitStroke="Red"
                                      DistanceStroke="Black"
                                  
                                      PointerMoved="OnPointerMoved"
          />
        
        <GridSplitter Grid.Row="1" />

        <TabControl Grid.Row="2" DockPanel.Dock="Bottom" Background="White" BorderBrush="Whitesmoke" BorderThickness="0,1,0,0">
          <TabItem Header="Shaped Buffer">
            <ListBox Name="_buffer" Grid.IsSharedSizeScope="True" ScrollViewer.HorizontalScrollBarVisibility="Auto" SelectionMode="Multiple" SelectionChanged="OnBufferSelectionChanged" Background="Transparent">
              <ListBox.Styles>
                <Style Selector="ListBoxItem">
                  <Setter Property="Padding" Value="0"/>
                  <Setter Property="Background" Value="White" />
                </Style>
              </ListBox.Styles>
              <Border Background="WhiteSmoke" BorderBrush="Silver" BorderThickness="0,1">
                <local:GridRow ColumnSpacing="10">
                  <TextBlock Text="" />
                  <TextBlock Text="Index" />
                  <TextBlock Text="Characters" />
                  <TextBlock Text="Codepoints" />
                  <TextBlock Text="Glyph" />
                  <TextBlock Text="Glyph ID" />
                  <TextBlock Text="Advance" />
                  <TextBlock Text="Offset" />
                  <TextBlock Text="Ink Bounds" />
                </local:GridRow>
              </Border>
            </ListBox>
          </TabItem>
          <TabItem Header="Character Hits">
            <ListBox Name="_hits" Grid.IsSharedSizeScope="True" ScrollViewer.HorizontalScrollBarVisibility="Auto" SelectionChanged="OnHitsSelectionChanged" Background="Transparent">
              <ListBox.Styles>
                <Style Selector="ListBoxItem">
                  <Setter Property="Padding" Value="0"/>
                  <Setter Property="Background" Value="White" />
                </Style>
              </ListBox.Styles>
              <Border Background="WhiteSmoke" BorderBrush="Silver" BorderThickness="0,1">
                <local:GridRow ColumnSpacing="10">
                  <TextBlock Text="" />
                  <TextBlock Text="Backspace Hit" />
                  <TextBlock Text="Previous Hit" />
                  <TextBlock Text="Index" />
                  <TextBlock Text="Next Hit" />
                  <TextBlock Text="Codepoint" />
                  <TextBlock Text="Character" />
                  <TextBlock Text="Distance" />
                </local:GridRow>
              </Border>
            </ListBox>
          </TabItem>
        </TabControl>
      </Grid>
    </DockPanel>
</Window>