Don't know how to detect when XXX is activated/deactivated, you may need to implement IActivationForViewFetcher

Don't know how to detect when Avalonia.MusicStore.Views.MainWindow is activated/deactivated, you may need to implement IActivationForViewFetcher

ReactiveWindowを継承し始めた途端に例外が発生。

UseReactiveUIの宣言漏れ。

sealed class Program
{
    // Initialization code. Don't use any Avalonia, third-party APIs or any
    // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
    // yet and stuff might break.
    [STAThread]
    public static void Main(string[] args) => BuildAvaloniaApp()
        .StartWithClassicDesktopLifetime(args);

    // Avalonia configuration, don't remove; also used by visual designer.
    public static AppBuilder BuildAvaloniaApp()
        => AppBuilder.Configure<App>()
            .UsePlatformDetect()
            .WithInterFont()
            .LogToTrace()
            .UseReactiveUI();
}

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