XAML-Map-Control/MapUiTools/Shared/MenuButton.cs

using System.Linq;
using System.Threading.Tasks;
#if WPF
using System.Windows;
using System.Windows.Controls;
#elif UWP
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
#elif WINUI
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
#elif AVALONIA
using Avalonia.Controls;
using DependencyProperty = Avalonia.AvaloniaProperty;
#endif

namespace MapControl.UiTools;

public partial class MenuButton : Button
{
    public static readonly DependencyProperty MapProperty =
        DependencyPropertyHelper.Register<MenuButton, MapBase>(nameof(Map), null,
            async (button, oldValue, newValue) => await button.Initialize());

    public MapBase Map
    {
        get => (MapBase)GetValue(MapProperty);
        set => SetValue(MapProperty, value);
    }

    private async Task Initialize()
    {
        if (Map != null)
        {
            DataContext = Map;

            var initialItem =
                Items.OfType<MapMenuItem>().FirstOrDefault(item => item.IsChecked) ??
                Items.OfType<MapMenuItem>().FirstOrDefault();

            if (initialItem != null)
            {
                initialItem.IsChecked = true;

                await initialItem.ExecuteAsync(Map);
            }
        }
    }
}