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

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="ControlCatalog.Pages.CommandBarEventsPage">
  <UserControl.Resources>
    <StreamGeometry x:Key="AddIcon">M19,13H13V19H11V13H5V11H11V5H13V11H19V13Z</StreamGeometry>
    <StreamGeometry x:Key="SaveIcon">M15,9H5V5H15M12,19A3,3 0 0,1 9,16A3,3 0 0,1 12,13A3,3 0 0,1 15,16A3,3 0 0,1 12,19M17,3H5C3.89,3 3,3.9 3,5V19A2,2 0 0,0 5,21H19A2,2 0 0,0 21,19V7L17,3Z</StreamGeometry>
    <StreamGeometry x:Key="ShareIcon">M18,16.08C17.24,16.08 16.56,16.38 16.04,16.85L8.91,12.7C8.96,12.47 9,12.24 9,12C9,11.76 8.96,11.53 8.91,11.3L15.96,7.19C16.5,7.69 17.21,8 18,8A3,3 0 0,0 21,5A3,3 0 0,0 18,2A3,3 0 0,0 15,5C15,5.24 15.04,5.47 15.09,5.7L8.04,9.81C7.5,9.31 6.79,9 6,9A3,3 0 0,0 3,12A3,3 0 0,0 6,15C6.79,15 7.5,14.69 8.04,14.19L15.16,18.34C15.11,18.55 15.08,18.77 15.08,19C15.08,20.61 16.39,21.91 18,21.91C19.61,21.91 20.92,20.61 20.92,19C20.92,17.39 19.61,16.08 18,16.08Z</StreamGeometry>
    <StreamGeometry x:Key="ExportIcon">M14,2H6A2,2 0 0,0 4,4V20A2,2 0 0,0 6,22H18A2,2 0 0,0 20,20V8L14,2M18,20H6V4H13V9H18V20M16,11V18.1L13.9,16L11.1,18.8L8.3,16L11.1,13.2L9,11.1L16,11Z</StreamGeometry>
    <StreamGeometry x:Key="DeleteIcon">M19,4H15.5L14.5,3H9.5L8.5,4H5V6H19M6,19A2,2 0 0,0 8,21H16A2,2 0 0,0 18,19V7H6V19Z</StreamGeometry>
  </UserControl.Resources>

  <DockPanel>
    <ScrollViewer DockPanel.Dock="Right" Width="280">
      <StackPanel Margin="12" Spacing="8">
        <TextBlock Text="Actions" FontWeight="SemiBold" FontSize="16"
                   Foreground="{DynamicResource SystemControlHighlightAccentBrush}" />

        <CheckBox x:Name="IsOpenCheck"
                  Content="IsOpen"
                  IsCheckedChanged="OnIsOpenChanged" />

        <Button Content="+ Add Primary"
                HorizontalAlignment="Stretch"
                Click="OnAddPrimary" />

        <Button Content="- Remove Primary"
                HorizontalAlignment="Stretch"
                Click="OnRemovePrimary" />

        <Button Content="+ Add Secondary"
                HorizontalAlignment="Stretch"
                Click="OnAddSecondary" />

        <Button Content="- Remove Secondary"
                HorizontalAlignment="Stretch"
                Click="OnRemoveSecondary" />

        <Button Content="Clear Log"
                HorizontalAlignment="Stretch"
                Click="OnClearLog" />

        <Separator />

        <TextBlock Text="State" FontWeight="SemiBold" />
        <TextBlock x:Name="StateText"
                   FontSize="12"
                   Opacity="0.7"
                   TextWrapping="Wrap" />

        <Separator />

        <TextBlock Text="About" FontWeight="SemiBold" />
        <TextBlock FontSize="12" Opacity="0.7" TextWrapping="Wrap"
                   Text="Opening/Opened fire when the overflow opens. Closing/Closed fire when it closes. The log also records item clicks and command execution while the state panel reflects IsOpen, HasSecondaryCommands, and IsOverflowButtonVisible in real time." />
      </StackPanel>
    </ScrollViewer>

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

    <ScrollViewer>
      <StackPanel Spacing="12" Margin="12,12,12,0">
        <TextBlock Classes="h2">Observe CommandBar overflow events, item invocation, and state changes while opening, closing, and editing the primary and secondary command sets.</TextBlock>

        <CommandBar x:Name="DemoBar"
                    OverflowButtonVisibility="Auto">
          <CommandBar.PrimaryCommands>
            <AppBarButton Label="New"><AppBarButton.Icon><PathIcon Data="{StaticResource AddIcon}" /></AppBarButton.Icon></AppBarButton>
            <AppBarButton Label="Save"><AppBarButton.Icon><PathIcon Data="{StaticResource SaveIcon}" /></AppBarButton.Icon></AppBarButton>
            <AppBarButton Label="Share"><AppBarButton.Icon><PathIcon Data="{StaticResource ShareIcon}" /></AppBarButton.Icon></AppBarButton>
          </CommandBar.PrimaryCommands>
          <CommandBar.SecondaryCommands>
            <AppBarButton Label="Export"><AppBarButton.Icon><PathIcon Data="{StaticResource ExportIcon}" /></AppBarButton.Icon></AppBarButton>
            <AppBarButton Label="Delete"><AppBarButton.Icon><PathIcon Data="{StaticResource DeleteIcon}" /></AppBarButton.Icon></AppBarButton>
          </CommandBar.SecondaryCommands>
        </CommandBar>

        <Border BorderBrush="{DynamicResource SystemControlForegroundBaseMediumLowBrush}"
                BorderThickness="1"
                CornerRadius="6"
                Padding="10">
          <StackPanel Spacing="6">
            <TextBlock Text="Event Log" FontWeight="SemiBold" />
            <TextBlock x:Name="EventLogText"
                       FontFamily="Consolas, Menlo, monospace"
                       FontSize="12"
                       TextWrapping="Wrap"
                       MinHeight="140"
                       Opacity="0.8"
                       Text="Ready" />
          </StackPanel>
        </Border>
      </StackPanel>
    </ScrollViewer>
  </DockPanel>
</UserControl>