feat: add default template.

demo/Ursa.Demo/Models/MenuKeys.cs

@@ -13,6 +13,7 @@ public static class MenuKeys
     public const string MenuKeyIconButton = "IconButton";
     public const string MenuKeyKeyGestureInput = "KeyGestureInput";
     public const string MenuKeyLoading = "Loading";
+    public const string MenuKeyMessageBox = "MessageBox";
     public const string MenuKeyNavigation = "Navigation";
     public const string MenuKeyPagination = "Pagination";
     public const string MenuKeyTagInput = "TagInput";

demo/Ursa.Demo/Pages/MessageBoxDemo.axaml

@@ -0,0 +1,13 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             xmlns:vm="using:Ursa.Demo.ViewModels"
+             x:DataType="vm:MessageBoxDemoViewModel"
+             x:CompileBindings="True"
+             x:Class="Ursa.Demo.Pages.MessageBoxDemo">
+    <StackPanel HorizontalAlignment="Left">
+        <Button Content="Default" Command="{Binding DefaultMessageBoxCommand}"></Button>
+    </StackPanel>
+</UserControl>

demo/Ursa.Demo/Pages/MessageBoxDemo.axaml.cs

@@ -0,0 +1,15 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using Ursa.Demo.ViewModels;
+
+namespace Ursa.Demo.Pages;
+
+public partial class MessageBoxDemo : UserControl
+{
+    public MessageBoxDemo()
+    {
+        InitializeComponent();
+        this.DataContext = new MessageBoxDemoViewModel();
+    }
+}

demo/Ursa.Demo/ViewModels/MainViewViewModel.cs

@@ -35,6 +35,7 @@ public class MainViewViewModel : ViewModelBase
             MenuKeys.MenuKeyIpBox => new IPv4BoxDemoViewModel(),
             MenuKeys.MenuKeyKeyGestureInput => new KeyGestureInputDemoViewModel(),
             MenuKeys.MenuKeyLoading => new LoadingDemoViewModel(),
+            MenuKeys.MenuKeyMessageBox => new MessageBoxDemoViewModel(),
             MenuKeys.MenuKeyNavigation => new NavigationMenuDemoViewModel(),
             MenuKeys.MenuKeyPagination => new PaginationDemoViewModel(),
             MenuKeys.MenuKeyTagInput => new TagInputDemoViewModel(),

demo/Ursa.Demo/ViewModels/MenuViewModel.cs

@@ -22,6 +22,7 @@ public class MenuViewModel: ViewModelBase
             new() { MenuHeader = "IPv4Box", Key = MenuKeys.MenuKeyIpBox },
             new() { MenuHeader = "KeyGestureInput", Key = MenuKeys.MenuKeyKeyGestureInput },
             new() { MenuHeader = "Loading", Key = MenuKeys.MenuKeyLoading },
+            new() { MenuHeader = "Message Box", Key = MenuKeys.MenuKeyMessageBox },
             new() { MenuHeader = "Navigation", Key = MenuKeys.MenuKeyNavigation },
             new() { MenuHeader = "Pagination", Key = MenuKeys.MenuKeyPagination },
             new() { MenuHeader = "TagInput", Key = MenuKeys.MenuKeyTagInput },

demo/Ursa.Demo/ViewModels/MessageBoxDemoViewModel.cs

@@ -0,0 +1,22 @@
+using System.Threading.Tasks;
+using System.Windows.Input;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using Ursa.Controls;
+
+namespace Ursa.Demo.ViewModels;
+
+public class MessageBoxDemoViewModel: ObservableObject
+{
+    public ICommand DefaultMessageBoxCommand { get; set; }
+
+    public MessageBoxDemoViewModel()
+    {
+        DefaultMessageBoxCommand = new AsyncRelayCommand(OnDefaultMessageAsync);
+    }
+
+    private async Task OnDefaultMessageAsync()
+    {
+        await MessageBox.ShowAsync("Hello Message Box");
+    }
+}

demo/Ursa.Demo/Views/MainWindow.axaml

@@ -10,6 +10,8 @@
     d:DesignHeight="450"
     d:DesignWidth="800"
     x:CompileBindings="True"
+    ExtendClientAreaTitleBarHeightHint="48"
+    ExtendClientAreaToDecorationsHint="True"
     x:DataType="viewModels:MainWindowViewModel"
     Icon="/Assets/Ursa.ico"
     mc:Ignorable="d">