feat: add icon, improve demo.

demo/Ursa.Demo/Pages/MessageBoxDemo.axaml

@@ -1,17 +1,32 @@
-<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">
+<UserControl
+    x:Class="Ursa.Demo.Pages.MessageBoxDemo"
+    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"
+    xmlns:vm="using:Ursa.Demo.ViewModels"
+    d:DesignHeight="450"
+    d:DesignWidth="800"
+    x:CompileBindings="True"
+    x:DataType="vm:MessageBoxDemoViewModel"
+    mc:Ignorable="d">
+    <UserControl.Styles>
+        <Style Selector="Button">
+            <Setter Property="HorizontalAlignment" Value="Left" />
+            <Setter Property="Margin" Value="8"></Setter>
+        </Style>
+    </UserControl.Styles>
     <StackPanel HorizontalAlignment="Left">
-        <Button Content="Default" Command="{Binding DefaultMessageBoxCommand}"></Button>
-        <Button Content="OK" Command="{Binding OkCommand}" ></Button>
-        <Button Content="OKCancel" Command="{Binding OkCancelCommand}" ></Button>
-        <Button Content="YesNo" Command="{Binding YesNoCommand}" ></Button>
-        <Button Content="YesNoCancel" Command="{Binding YesNoCancelCommand}" ></Button>
+        <ComboBox ItemsSource="{Binding Icons}" SelectedItem="{Binding SelectedIcon}" />
+        <Button Command="{Binding DefaultMessageBoxCommand}" Content="Default" />
+        <Button Command="{Binding OkCommand}" Content="OK" />
+        <Button Command="{Binding OkCancelCommand}" Content="OKCancel" />
+        <Button Command="{Binding YesNoCommand}" Content="YesNo" />
+        <Button Command="{Binding YesNoCancelCommand}" Content="YesNoCancel" />
+        
+        <TextBlock>
+            <Run Text="Last Clicked Result: "></Run>
+            <Run Text="{Binding Result}"></Run>
+        </TextBlock>
     </StackPanel>
 </UserControl>

demo/Ursa.Demo/ViewModels/MessageBoxDemoViewModel.cs

@@ -1,4 +1,6 @@
-using System.Threading.Tasks;
+using System;
+using System.Collections.ObjectModel;
+using System.Threading.Tasks;
 using System.Windows.Input;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
@@ -13,6 +15,22 @@ public class MessageBoxDemoViewModel: ObservableObject
     public ICommand YesNoCommand { get; set; }
     public ICommand YesNoCancelCommand { get; set; }
     public ICommand OkCancelCommand { get; set; }
+    
+    public ObservableCollection<MessageBoxIcon> Icons { get; set; }
+    
+    private MessageBoxIcon _selectedIcon;
+    public MessageBoxIcon SelectedIcon
+    {
+        get => _selectedIcon;
+        set => SetProperty(ref _selectedIcon, value);
+    }
+
+    private MessageBoxResult _result;
+    public MessageBoxResult Result
+    {
+        get => _result;
+        set => SetProperty(ref _result, value);
+    }
 
     public MessageBoxDemoViewModel()
     {
@@ -21,30 +39,33 @@ public class MessageBoxDemoViewModel: ObservableObject
         YesNoCommand = new AsyncRelayCommand(OnYesNoAsync);
         YesNoCancelCommand = new AsyncRelayCommand(OnYesNoCancelAsync);
         OkCancelCommand = new AsyncRelayCommand(OnOkCancelAsync);
+        Icons = new ObservableCollection<MessageBoxIcon>(
+            Enum.GetValues<MessageBoxIcon>());
+        SelectedIcon = MessageBoxIcon.None;
     }
 
     private async Task OnDefaultMessageAsync()
     {
-        var result = await MessageBox.ShowAsync("Hello Message Box");
+        Result = await MessageBox.ShowAsync("Hello Message Box", icon: SelectedIcon);
     }
     
     private async Task OnOkAsync()
     {
-        var result = await MessageBox.ShowAsync("Hello Message Box", "Hello", MessageBoxButton.OK);
+        Result = await MessageBox.ShowAsync("Hello Message Box", "Hello", icon: SelectedIcon, button:MessageBoxButton.OK);
     }
     
     private async Task OnYesNoAsync()
     {
-        var result = await MessageBox.ShowAsync("Hello Message Box", "Hello", MessageBoxButton.YesNo);
+        Result = await MessageBox.ShowAsync("Hello Message Box", "Hello", icon: SelectedIcon, button: MessageBoxButton.YesNo);
     }
     
     private async Task OnYesNoCancelAsync()
     {
-        var result = await MessageBox.ShowAsync("Hello Message Box", "Hello", MessageBoxButton.YesNoCancel);
+        Result = await MessageBox.ShowAsync("Hello Message Box", "Hello", icon: SelectedIcon, button: MessageBoxButton.YesNoCancel);
     }
     
     private async Task OnOkCancelAsync()
     {
-        var result = await MessageBox.ShowAsync("Hello Message Box", "Hello", MessageBoxButton.OKCancel);
+        Result = await MessageBox.ShowAsync("Hello Message Box", "Hello", icon: SelectedIcon, button:MessageBoxButton.OKCancel);
     }
 }