Avalonia/samples/ControlCatalog/Pages/MenuPage.xaml

<UserControl xmlns="https://github.com/avaloniaui">
  <StackPanel Orientation="Vertical" Spacing="4">
    <TextBlock Classes="h1">Menu</TextBlock>
    <TextBlock Classes="h2">A window menu</TextBlock>

        <StackPanel Orientation="Horizontal"
              Margin="0,16,0,0"
              HorizontalAlignment="Center"
              Spacing="16">
            <StackPanel>
                <TextBlock Classes="h3" Margin="4 8">Defined in XAML</TextBlock>
                <Menu>
                    <MenuItem Header="_First">
                        <MenuItem Header="Standard _Menu Item"/>
                        <Separator/>
                        <MenuItem Header="Menu with _Submenu">
                            <MenuItem Header="Submenu _1"/>
                            <MenuItem Header="Submenu _2"/>
                        </MenuItem>
                        <MenuItem Header="Menu Item with _Icon">
                            <MenuItem.Icon>
                                <Image Source="resm:ControlCatalog.Assets.github_icon.png"/>
                            </MenuItem.Icon>
                        </MenuItem>
                        <MenuItem Header="Menu Item with _Checkbox">
                            <MenuItem.Icon>
                                <CheckBox BorderThickness="0" IsHitTestVisible="False" IsChecked="True"/>
                            </MenuItem.Icon>
                        </MenuItem>
                    </MenuItem>
                    <MenuItem Header="_Second">
                        <MenuItem Header="Second _Menu Item"/>
                    </MenuItem>
                </Menu>
            </StackPanel>

            <StackPanel>
                <TextBlock Classes="h3" Margin="4 8">Dyanamically generated</TextBlock>
                <Menu Items="{Binding MenuItems}">
                    <Menu.Styles>
                        <Style Selector="MenuItem">
                            <Setter Property="Header" Value="{Binding Header}"/>
                            <Setter Property="Items" Value="{Binding Items}"/>
                            <Setter Property="Command" Value="{Binding Command}"/>
                            <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
                        </Style>
                    </Menu.Styles>
                </Menu>
            </StackPanel>
        </StackPanel>
    </StackPanel>
</UserControl>