Avalonia/samples/ControlCatalog/Pages/CommandBar/CommandBarTogglePage.xaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="ControlCatalog.Pages.CommandBarTogglePage">
  <UserControl.Resources>
    <StreamGeometry x:Key="BoldIcon">M15.6,10.79C17.04,10.07 18,8.64 18,7C18,4.79 16.21,3 14,3H7V21H14.73C16.78,21 18.5,19.37 18.5,17.32C18.5,15.82 17.72,14.53 16.5,13.77C16.2,13.59 15.9,13.44 15.6,13.32V10.79M10,6.5H13C13.83,6.5 14.5,7.17 14.5,8C14.5,8.83 13.83,9.5 13,9.5H10V6.5M13.5,17.5H10V14H13.5C14.33,14 15,14.67 15,15.5C15,16.33 14.33,17.5 13.5,17.5Z</StreamGeometry>
    <StreamGeometry x:Key="ItalicIcon">M10,4V7H12.21L8.79,15H6V18H14V15H11.79L15.21,7H18V4H10Z</StreamGeometry>
    <StreamGeometry x:Key="UnderlineIcon">M5,21H19V19H5V21M12,17A6,6 0 0,0 18,11V3H15.5V11A3.5,3.5 0 0,1 12,14.5A3.5,3.5 0 0,1 8.5,11V3H6V11A6,6 0 0,0 12,17Z</StreamGeometry>
    <StreamGeometry x:Key="FavoriteIcon">M12,21.35L10.55,20.03C5.4,15.36 2,12.27 2,8.5C2,5.41 4.42,3 7.5,3C9.24,3 10.91,3.81 12,5.08C13.09,3.81 14.76,3 16.5,3C19.58,3 22,5.41 22,8.5C22,12.27 18.6,15.36 13.45,20.03L12,21.35Z</StreamGeometry>
  </UserControl.Resources>

  <DockPanel>
    <ScrollViewer DockPanel.Dock="Right" Width="260">
      <StackPanel Margin="12" Spacing="8">
        <TextBlock Text="Configuration" FontWeight="SemiBold" FontSize="16"
                   Foreground="{DynamicResource SystemControlHighlightAccentBrush}" />
        <TextBlock Text="Toggle State" FontWeight="SemiBold" FontSize="13" />

        <CheckBox x:Name="ForceBoldCheck"
                  Content="Bold"
                  IsCheckedChanged="OnForceBoldChanged" />
        <CheckBox x:Name="ForceItalicCheck"
                  Content="Italic"
                  IsCheckedChanged="OnForceItalicChanged" />
        <CheckBox x:Name="ForceUnderlineCheck"
                  Content="Underline"
                  IsCheckedChanged="OnForceUnderlineChanged" />

        <Separator />

        <TextBlock Text="About" FontWeight="SemiBold" />
        <TextBlock Text="AppBarToggleButton maintains checked/unchecked state. When checked, it shows a highlight background. Bind IsChecked to a boolean property."
                   FontSize="12" Opacity="0.7" TextWrapping="Wrap" />
      </StackPanel>
    </ScrollViewer>

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

    <ScrollViewer>
      <StackPanel Spacing="12" Margin="12,12,12,0">
        <TextBlock Classes="h2">AppBarToggleButton supports on/off states for formatting and feature toggles.</TextBlock>

        <TextBlock Text="Text Formatting" FontWeight="SemiBold" />
        <CommandBar x:Name="FormatBar" OverflowButtonVisibility="Collapsed">
          <AppBarToggleButton x:Name="BoldToggle"
                              Label="Bold"
                              IsCheckedChanged="OnFormatChanged">
            <AppBarToggleButton.Icon><PathIcon Data="{StaticResource BoldIcon}" /></AppBarToggleButton.Icon>
          </AppBarToggleButton>
          <AppBarToggleButton x:Name="ItalicToggle"
                              Label="Italic"
                              IsCheckedChanged="OnFormatChanged">
            <AppBarToggleButton.Icon><PathIcon Data="{StaticResource ItalicIcon}" /></AppBarToggleButton.Icon>
          </AppBarToggleButton>
          <AppBarToggleButton x:Name="UnderlineToggle"
                              Label="Underline"
                              IsCheckedChanged="OnFormatChanged">
            <AppBarToggleButton.Icon><PathIcon Data="{StaticResource UnderlineIcon}" /></AppBarToggleButton.Icon>
          </AppBarToggleButton>
        </CommandBar>

        <TextBlock x:Name="FormatStatus"
                   Text="Active: (none)"
                   FontSize="13"
                   Opacity="0.7" />

        <Separator />

        <TextBlock Text="Favorite" FontWeight="SemiBold" />
        <CommandBar OverflowButtonVisibility="Collapsed">
          <AppBarToggleButton Label="Favorite">
            <AppBarToggleButton.Icon><PathIcon Data="{StaticResource FavoriteIcon}" /></AppBarToggleButton.Icon>
          </AppBarToggleButton>
        </CommandBar>
      </StackPanel>
    </ScrollViewer>
  </DockPanel>
</UserControl>