feat: add new Notification.

demo/Ursa.Demo/Pages/NotificationDemo.axaml

@@ -0,0 +1,34 @@
+<UserControl x:Class="Ursa.Demo.Pages.NotificationDemo"
+             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"
+             x:DataType="vm:NotificationDemoViewModel"
+             d:DesignHeight="450"
+             d:DesignWidth="800"
+             mc:Ignorable="d">
+    <Design.DataContext>
+        <vm:NotificationDemoViewModel />
+    </Design.DataContext>
+    <StackPanel>
+        <ToggleSwitch IsChecked="{Binding ShowClose}" Content="ShowClose"/>
+        <StackPanel Orientation="Horizontal" Spacing="20">
+            <Button Command="{Binding ShowNormal}" CommandParameter="{Binding $self.Content}" Content="Information" />
+            <Button Command="{Binding ShowNormal}" CommandParameter="{Binding $self.Content}" Content="Success" Classes="Success" />
+            <Button Command="{Binding ShowNormal}" CommandParameter="{Binding $self.Content}" Content="Warning" Classes="Warning" />
+            <Button Command="{Binding ShowNormal}" CommandParameter="{Binding $self.Content}" Content="Error" Classes="Danger" />
+        </StackPanel>
+        <StackPanel Orientation="Horizontal" Spacing="20">
+            <StackPanel.Styles>
+                <Style Selector="Button">
+                    <Setter Property="Theme" Value="{DynamicResource SolidButton}" />
+                </Style>
+            </StackPanel.Styles>
+            <Button Command="{Binding ShowLight}" CommandParameter="{Binding $self.Content}" Content="Information" />
+            <Button Command="{Binding ShowLight}" CommandParameter="{Binding $self.Content}" Content="Success" Classes="Success" />
+            <Button Command="{Binding ShowLight}" CommandParameter="{Binding $self.Content}" Content="Warning" Classes="Warning" />
+            <Button Command="{Binding ShowLight}" CommandParameter="{Binding $self.Content}" Content="Error" Classes="Danger" />
+        </StackPanel>
+    </StackPanel>
+</UserControl>

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

@@ -0,0 +1,25 @@
+using Avalonia;
+using Avalonia.Controls;
+using Ursa.Controls;
+using Ursa.Demo.ViewModels;
+
+namespace Ursa.Demo.Pages;
+
+public partial class NotificationDemo : UserControl
+{
+    private NotificationDemoViewModel _viewModel;
+
+    public NotificationDemo()
+    {
+        InitializeComponent();
+        _viewModel = new NotificationDemoViewModel();
+        DataContext = _viewModel;
+    }
+
+    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+    {
+        base.OnAttachedToVisualTree(e);
+        var topLevel = TopLevel.GetTopLevel(this);
+        _viewModel.NotificationManager = new WindowNotificationManager(topLevel) { MaxItems = 3 };
+    }
+}

demo/Ursa.Demo/ViewModels/MainViewViewModel.cs

@@ -52,6 +52,7 @@ public class MainViewViewModel : ViewModelBase
             MenuKeys.MenuKeyMessageBox => new MessageBoxDemoViewModel(),
             MenuKeys.MenuKeyMultiComboBox => new MultiComboBoxDemoViewModel(),
             MenuKeys.MenuKeyNavMenu => new NavMenuDemoViewModel(),
+            MenuKeys.MenuKeyNotification => new NotificationDemoViewModel(),
             MenuKeys.MenuKeyNumberDisplayer => new NumberDisplayerDemoViewModel(),
             MenuKeys.MenuKeyNumericUpDown => new NumericUpDownDemoViewModel(),
             MenuKeys.MenuKeyNumPad => new NumPadDemoViewModel(),

demo/Ursa.Demo/ViewModels/MenuViewModel.cs

@@ -37,6 +37,7 @@ public class MenuViewModel: ViewModelBase
             new() { MenuHeader = "Message Box", Key = MenuKeys.MenuKeyMessageBox },
             new() { MenuHeader = "MultiComboBox", Key = MenuKeys.MenuKeyMultiComboBox, Status = "Updated" },
             new() { MenuHeader = "Nav Menu", Key = MenuKeys.MenuKeyNavMenu },
+            new() { MenuHeader = "Notification", Key = MenuKeys.MenuKeyNotification },
             new() { MenuHeader = "Number Displayer", Key = MenuKeys.MenuKeyNumberDisplayer, Status = "New" }, 
             new() { MenuHeader = "Numeric UpDown", Key = MenuKeys.MenuKeyNumericUpDown },
             new() { MenuHeader = "NumPad", Key = MenuKeys.MenuKeyNumPad },
@@ -88,6 +89,7 @@ public static class MenuKeys
     public const string MenuKeyMessageBox = "MessageBox";
     public const string MenuKeyMultiComboBox = "MultiComboBox";
     public const string MenuKeyNavMenu = "NavMenu";
+    public const string MenuKeyNotification = "Notification";
     public const string MenuKeyNumberDisplayer = "NumberDisplayer";
     public const string MenuKeyNumericUpDown = "NumericUpDown";
     public const string MenuKeyNumPad = "NumPad";

demo/Ursa.Demo/ViewModels/NotificationDemoViewModel.cs

@@ -0,0 +1,42 @@
+using System;
+using Avalonia.Controls.Notifications;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using Notification = Ursa.Controls.Notification;
+using WindowNotificationManager = Ursa.Controls.WindowNotificationManager;
+
+namespace Ursa.Demo.ViewModels;
+
+public partial class NotificationDemoViewModel : ObservableObject
+{
+    public WindowNotificationManager? NotificationManager { get; set; }
+
+    [ObservableProperty] private bool _showClose = true;
+
+    [RelayCommand]
+    public void ShowNormal(object obj)
+    {
+        if (obj is string s)
+        {
+            Enum.TryParse<NotificationType>(s, out var notificationType);
+            NotificationManager?.Show(
+                new Notification("Welcome", "This is message"),
+                showClose: ShowClose,
+                type: notificationType);
+        }
+    }
+
+    [RelayCommand]
+    public void ShowLight(object obj)
+    {
+        if (obj is string s)
+        {
+            Enum.TryParse<NotificationType>(s, out var notificationType);
+            NotificationManager?.Show(
+                new Notification("Welcome", "This is message"),
+                showClose: ShowClose,
+                type: notificationType,
+                classes: ["Light"]);
+        }
+    }
+}

src/Ursa.Themes.Semi/Controls/Notification.axaml

@@ -0,0 +1,233 @@
+<ResourceDictionary xmlns="https://github.com/avaloniaui"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:u="https://irihi.tech/ursa">
+    <Design.PreviewWith>
+        <ThemeVariantScope RequestedThemeVariant="Dark">
+            <StackPanel Orientation="Vertical">
+                <u:NotificationCard ShowClose="False" />
+                <u:NotificationCard>
+                    Hello, Ursa!
+                </u:NotificationCard>
+                <u:NotificationCard NotificationType="Success">
+                    <u:Notification Title="Welcome" Content="Hello, Ursa!" />
+                </u:NotificationCard>
+            </StackPanel>
+        </ThemeVariantScope>
+    </Design.PreviewWith>
+
+    <ControlTheme x:Key="{x:Type u:WindowNotificationManager}" TargetType="u:WindowNotificationManager">
+        <Setter Property="Margin" Value="0" />
+        <Setter Property="Template">
+            <ControlTemplate>
+                <ReversibleStackPanel Name="PART_Items" />
+            </ControlTemplate>
+        </Setter>
+        <Style Selector="^ /template/ ReversibleStackPanel#PART_Items">
+            <Setter Property="VerticalAlignment" Value="Top" />
+            <Setter Property="HorizontalAlignment" Value="Center" />
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="{x:Type u:NotificationCard}" TargetType="u:NotificationCard">
+        <Setter Property="UseLayoutRounding" Value="True" />
+        <Setter Property="RenderTransformOrigin" Value="50%,75%" />
+        <Setter Property="BorderThickness" Value="{DynamicResource NotificationCardBorderThickness}" />
+        <Setter Property="BorderBrush" Value="{DynamicResource NotificationCardBorderBrush}" />
+        <Setter Property="Background" Value="{DynamicResource NotificationCardBackground}" />
+        <Setter Property="CornerRadius" Value="{DynamicResource NotificationCardCornerRadius}" />
+        <Setter Property="Template">
+            <ControlTemplate TargetType="u:NotificationCard">
+                <LayoutTransformControl x:Name="PART_LayoutTransformControl" UseRenderTransform="True">
+                    <Border
+                        Margin="{DynamicResource NotificationCardMargin}"
+                        Background="{TemplateBinding Background}"
+                        CornerRadius="{TemplateBinding CornerRadius}">
+                        <Border
+                            x:Name="PART_RootBorder"
+                            Padding="{DynamicResource NotificationCardPadding}"
+                            BoxShadow="{DynamicResource NotificationCardBoxShadow}"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness}"
+                            CornerRadius="{TemplateBinding CornerRadius}">
+                            <Grid ColumnDefinitions="Auto,*,Auto">
+                                <PathIcon
+                                    x:Name="NotificationIcon"
+                                    Grid.Column="0"
+                                    Width="{DynamicResource NotificationCardIconWidth}"
+                                    Height="{DynamicResource NotificationCardIconHeight}"
+                                    Margin="{DynamicResource NotificationCardIconMargin}"
+                                    VerticalAlignment="Top"
+                                    IsVisible="False"
+                                    Data="{DynamicResource NotificationCardInformationIconPathData}" />
+                                <ContentControl
+                                    x:Name="PART_Content"
+                                    Grid.Column="1"
+                                    VerticalContentAlignment="Center"
+                                    Content="{TemplateBinding Content}">
+                                    <ContentControl.DataTemplates>
+                                        <DataTemplate DataType="u:INotification">
+                                            <StackPanel Spacing="{DynamicResource NotificationCardTitleSpacing}">
+                                                <SelectableTextBlock
+                                                    Foreground="{DynamicResource NotificationCardTitleForeground}"
+                                                    FontSize="{DynamicResource NotificationCardTitleFontSize}"
+                                                    FontWeight="{DynamicResource NotificationCardTitleFontWeight}"
+                                                    IsVisible="{Binding Title, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
+                                                    Text="{Binding Title}" />
+                                                <SelectableTextBlock
+                                                    Foreground="{DynamicResource NotificationCardMessageForeground}"
+                                                    FontSize="{DynamicResource NotificationCardMessageFontSize}"
+                                                    FontWeight="{DynamicResource NotificationCardMessageFontWeight}"
+                                                    Text="{Binding Content}"
+                                                    TextWrapping="Wrap" />
+                                            </StackPanel>
+                                        </DataTemplate>
+                                        <DataTemplate DataType="x:String">
+                                            <SelectableTextBlock
+                                                Foreground="{DynamicResource NotificationCardMessageForeground}"
+                                                FontSize="{DynamicResource NotificationCardMessageFontSize}"
+                                                FontWeight="{DynamicResource NotificationCardMessageFontWeight}"
+                                                Text="{Binding}"
+                                                TextWrapping="Wrap" />
+                                        </DataTemplate>
+                                    </ContentControl.DataTemplates>
+                                </ContentControl>
+                                <Button
+                                    x:Name="PART_CloseButton"
+                                    Grid.Column="2"
+                                    VerticalAlignment="Top"
+                                    HorizontalAlignment="Right"
+                                    Theme="{StaticResource NotificationCloseButton}"
+                                    IsVisible="{TemplateBinding ShowClose}"
+                                    u:MessageCard.CloseOnClick="True" />
+                            </Grid>
+                        </Border>
+                    </Border>
+                </LayoutTransformControl>
+            </ControlTemplate>
+        </Setter>
+
+        <ControlTheme.Animations>
+            <Animation
+                Easing="QuadraticEaseIn"
+                FillMode="Forward"
+                Duration="0:0:0.3">
+                <KeyFrame Cue="0%">
+                    <Setter Property="Opacity" Value="0" />
+                </KeyFrame>
+                <KeyFrame Cue="100%">
+                    <Setter Property="Opacity" Value="1" />
+                </KeyFrame>
+                <KeyFrame KeySpline="0.22,0.57,0.02,1.2" Cue="0%">
+                    <Setter Property="TranslateTransform.Y" Value="-100" />
+                </KeyFrame>
+                <KeyFrame KeySpline="0.22,0.57,0.02,1.2" Cue="100%">
+                    <Setter Property="TranslateTransform.Y" Value="0" />
+                </KeyFrame>
+            </Animation>
+        </ControlTheme.Animations>
+
+        <Style Selector="^[IsClosing=true] /template/ LayoutTransformControl#PART_LayoutTransformControl">
+            <Setter Property="RenderTransformOrigin" Value="50%,0%" />
+            <Style.Animations>
+                <Animation
+                    Easing="QuadraticEaseOut"
+                    FillMode="Forward"
+                    Duration="0:0:0.3">
+                    <KeyFrame Cue="0%">
+                        <Setter Property="Opacity" Value="1" />
+                    </KeyFrame>
+                    <KeyFrame Cue="100%">
+                        <Setter Property="Opacity" Value="0" />
+                    </KeyFrame>
+                    <KeyFrame KeySpline="0.22,0.57,0.02,1.2" Cue="0%">
+                        <Setter Property="TranslateTransform.Y" Value="0" />
+                    </KeyFrame>
+                    <KeyFrame KeySpline="0.22,0.57,0.02,1.2" Cue="100%">
+                        <Setter Property="TranslateTransform.Y" Value="-100" />
+                    </KeyFrame>
+                </Animation>
+            </Style.Animations>
+        </Style>
+
+        <Style Selector="^[IsClosing=true]">
+            <Style.Animations>
+                <Animation
+                    Easing="QuadraticEaseOut"
+                    FillMode="Forward"
+                    Duration="0:0:0.3">
+                    <KeyFrame Cue="100%">
+                        <Setter Property="IsClosed" Value="True" />
+                    </KeyFrame>
+                </Animation>
+            </Style.Animations>
+        </Style>
+
+        <Style Selector="^:information /template/ PathIcon#NotificationIcon">
+            <Setter Property="IsVisible" Value="True" />
+            <Setter Property="Foreground" Value="{DynamicResource NotificationCardInformationIconForeground}" />
+            <Setter Property="Data" Value="{DynamicResource NotificationCardInformationIconPathData}" />
+        </Style>
+        <Style Selector="^:success /template/ PathIcon#NotificationIcon">
+            <Setter Property="IsVisible" Value="True" />
+            <Setter Property="Foreground" Value="{DynamicResource NotificationCardSuccessIconForeground}" />
+            <Setter Property="Data" Value="{DynamicResource NotificationCardSuccessIconPathData}" />
+        </Style>
+        <Style Selector="^:warning /template/ PathIcon#NotificationIcon">
+            <Setter Property="IsVisible" Value="True" />
+            <Setter Property="Foreground" Value="{DynamicResource NotificationCardWarningIconForeground}" />
+            <Setter Property="Data" Value="{DynamicResource NotificationCardWarningIconPathData}" />
+        </Style>
+        <Style Selector="^:error /template/ PathIcon#NotificationIcon">
+            <Setter Property="IsVisible" Value="True" />
+            <Setter Property="Foreground" Value="{DynamicResource NotificationCardErrorIconForeground}" />
+            <Setter Property="Data" Value="{DynamicResource NotificationCardErrorIconPathData}" />
+        </Style>
+
+        <Style Selector="^.Light">
+            <Setter Property="Background" Value="{DynamicResource SemiColorBackground0}" />
+            <Style Selector="^:information /template/ Border#PART_RootBorder">
+                <Setter Property="BorderBrush" Value="{DynamicResource SemiColorInformation}" />
+                <Setter Property="Background" Value="{DynamicResource SemiColorInformationLight}" />
+            </Style>
+            <Style Selector="^:success /template/ Border#PART_RootBorder">
+                <Setter Property="BorderBrush" Value="{DynamicResource SemiColorSuccess}" />
+                <Setter Property="Background" Value="{DynamicResource SemiColorSuccessLight}" />
+            </Style>
+            <Style Selector="^:warning /template/ Border#PART_RootBorder">
+                <Setter Property="BorderBrush" Value="{DynamicResource SemiColorWarning}" />
+                <Setter Property="Background" Value="{DynamicResource SemiColorWarningLight}" />
+            </Style>
+            <Style Selector="^:error /template/ Border#PART_RootBorder">
+                <Setter Property="BorderBrush" Value="{DynamicResource SemiColorDanger}" />
+                <Setter Property="Background" Value="{DynamicResource SemiColorDangerLight}" />
+            </Style>
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="NotificationCloseButton" TargetType="Button">
+        <Setter Property="CornerRadius" Value="6" />
+        <Setter Property="Height" Value="24" />
+        <Setter Property="Width" Value="24" />
+        <Setter Property="Cursor" Value="Hand" />
+        <Setter Property="Template">
+            <ControlTemplate TargetType="Button">
+                <Border
+                    Name="PART_Border"
+                    Padding="{TemplateBinding Padding}"
+                    Background="Transparent"
+                    CornerRadius="{TemplateBinding CornerRadius}">
+                    <PathIcon
+                        Width="10"
+                        Height="10"
+                        Data="{DynamicResource WindowCloseIconGlyph}" />
+                </Border>
+            </ControlTemplate>
+        </Setter>
+        <Style Selector="^:pointerover /template/ Border">
+            <Setter Property="Background" Value="{DynamicResource ButtonDefaultPointeroverBackground}" />
+        </Style>
+        <Style Selector="^:pressed /template/ Border">
+            <Setter Property="Background" Value="{DynamicResource ButtonDefaultPressedBackground}" />
+        </Style>
+    </ControlTheme>
+</ResourceDictionary>

src/Ursa.Themes.Semi/Controls/_index.axaml

@@ -29,6 +29,7 @@
         <ResourceInclude Source="MessageBox.axaml" />
         <ResourceInclude Source="MultiComboBox.axaml" />
         <ResourceInclude Source="NavMenu.axaml" />
+        <ResourceInclude Source="Notification.axaml" />
         <ResourceInclude Source="NumericUpDown.axaml" />
         <ResourceInclude Source="NumPad.axaml" />
         <ResourceInclude Source="NumberDisplayer.axaml" />

src/Ursa/Controls/Notification/INotification.cs

@@ -0,0 +1,17 @@
+namespace Ursa.Controls;
+
+/// <summary>
+/// Represents a notification that can be shown in a window or by the host operating system.
+/// </summary>
+public interface INotification : IMessage
+{
+    /// <summary>
+    /// Gets the Title of the notification.
+    /// </summary>
+    string? Title { get; }
+
+    /// <summary>
+    /// Gets the Content of the notification.
+    /// </summary>
+    string? Content { get; }
+}

src/Ursa/Controls/Notification/INotificationManager.cs

@@ -0,0 +1,14 @@
+namespace Ursa.Controls;
+
+/// <summary>
+/// Represents a notification manager that can be used to show notifications in a window or using
+/// the host operating system.
+/// </summary>
+public interface INotificationManager
+{
+    /// <summary>
+    /// Show a notification.
+    /// </summary>
+    /// <param name="notification">The notification to be displayed.</param>
+    void Show(INotification notification);
+}

src/Ursa/Controls/Notification/Notification.cs

@@ -0,0 +1,103 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using Avalonia.Controls.Notifications;
+
+namespace Ursa.Controls;
+
+/// <summary>
+/// A notification that can be shown in a window or by the host operating system.
+/// </summary>
+/// <remarks>
+/// This class represents a notification that can be displayed either in a window using
+/// <see cref="WindowNotificationManager"/> or by the host operating system (to be implemented).
+/// </remarks>
+public class Notification : INotification, INotifyPropertyChanged
+{
+    private string? _title, _content;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Notification"/> class.
+    /// </summary>
+    /// <param name="title">The title of the notification.</param>
+    /// <param name="content">The content to be displayed in the notification.</param>
+    /// <param name="type">The <see cref="NotificationType"/> of the notification.</param>
+    /// <param name="expiration">The expiry time at which the notification will close.
+    /// Use <see cref="TimeSpan.Zero"/> for notifications that will remain open.</param>
+    /// <param name="showClose">A value indicating whether the notification should show a close button.</param>
+    /// <param name="onClick">An Action to call when the notification is clicked.</param>
+    /// <param name="onClose">An Action to call when the notification is closed.</param>
+    public Notification(
+        string? title,
+        string? content,
+        NotificationType type = NotificationType.Information,
+        TimeSpan? expiration = null,
+        bool showClose = true,
+        Action? onClick = null,
+        Action? onClose = null)
+    {
+        Title = title;
+        Content = content;
+        Type = type;
+        Expiration = expiration ?? TimeSpan.FromSeconds(3);
+        ShowClose = showClose;
+        OnClick = onClick;
+        OnClose = onClose;
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Notification"/> class.
+    /// </summary>
+    public Notification() : this(null, null)
+    {
+    }
+
+    /// <inheritdoc/>
+    public string? Title
+    {
+        get => _title;
+        set
+        {
+            if (_title != value)
+            {
+                _title = value;
+                OnPropertyChanged();
+            }
+        }
+    }
+
+    /// <inheritdoc/>
+    public string? Content
+    {
+        get => _content;
+        set
+        {
+            if (_content != value)
+            {
+                _content = value;
+                OnPropertyChanged();
+            }
+        }
+    }
+
+    /// <inheritdoc/>
+    public NotificationType Type { get; set; }
+
+    /// <inheritdoc/>
+    public TimeSpan Expiration { get; set; }
+
+    /// <inheritdoc/>
+    public bool ShowClose { get; }
+
+    /// <inheritdoc/>
+    public Action? OnClick { get; set; }
+
+    /// <inheritdoc/>
+    public Action? OnClose { get; set; }
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+
+    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
+    {
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}

src/Ursa/Controls/Notification/NotificationCard.cs

@@ -0,0 +1,6 @@
+namespace Ursa.Controls;
+
+/// <summary>
+/// Control that represents and displays a notification.
+/// </summary>
+public class NotificationCard : MessageCard;

src/Ursa/Controls/Notification/WindowNotificationManager.cs

@@ -0,0 +1,171 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Notifications;
+using Avalonia.Layout;
+using Avalonia.Threading;
+
+namespace Ursa.Controls;
+
+/// <summary>
+/// An <see cref="INotificationManager"/> that displays notifications in a <see cref="Window"/>.
+/// </summary>
+[PseudoClasses(PC_TopLeft, PC_TopRight, PC_BottomLeft, PC_BottomRight, PC_TopCenter, PC_BottomCenter)]
+public class WindowNotificationManager : WindowMessageManager, INotificationManager
+{
+    public const string PC_TopLeft = ":topleft";
+    public const string PC_TopRight = ":topright";
+    public const string PC_BottomLeft = ":bottomleft";
+    public const string PC_BottomRight = ":bottomright";
+    public const string PC_TopCenter = ":topcenter";
+    public const string PC_BottomCenter = ":bottomcenter";
+
+    /// <summary>
+    /// Defines the <see cref="Position"/> property.
+    /// </summary>
+    public static readonly StyledProperty<NotificationPosition> PositionProperty =
+        AvaloniaProperty.Register<WindowNotificationManager, NotificationPosition>(nameof(Position),
+            NotificationPosition.TopRight);
+
+    /// <summary>
+    /// Defines which corner of the screen notifications can be displayed in.
+    /// </summary>
+    /// <seealso cref="NotificationPosition"/>
+    public NotificationPosition Position
+    {
+        get => GetValue(PositionProperty);
+        set => SetValue(PositionProperty, value);
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WindowNotificationManager"/> class.
+    /// </summary>
+    /// <param name="host">The TopLevel that will host the control.</param>
+    public WindowNotificationManager(TopLevel? host) : this()
+    {
+        if (host is not null)
+        {
+            InstallFromTopLevel(host);
+        }
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WindowNotificationManager"/> class.
+    /// </summary>
+    public WindowNotificationManager()
+    {
+        UpdatePseudoClasses(Position);
+    }
+
+    static WindowNotificationManager()
+    {
+        HorizontalAlignmentProperty.OverrideDefaultValue<WindowNotificationManager>(HorizontalAlignment.Stretch);
+        VerticalAlignmentProperty.OverrideDefaultValue<WindowNotificationManager>(VerticalAlignment.Stretch);
+    }
+
+    /// <inheritdoc/>
+    public void Show(INotification content)
+    {
+        Show(content, content.Type, content.Expiration, content.ShowClose, content.OnClick, content.OnClose);
+    }
+
+    /// <inheritdoc/>
+    public override void Show(object content)
+    {
+        if (content is INotification notification)
+        {
+            Show(notification, notification.Type, notification.Expiration, notification.ShowClose, notification.OnClick,
+                notification.OnClose);
+        }
+        else
+        {
+            Show(content, NotificationType.Information);
+        }
+    }
+
+    /// <summary>
+    /// Shows a Notification
+    /// </summary>
+    /// <param name="content">the content of the notification</param>
+    /// <param name="type">the type of the notification</param>
+    /// <param name="expiration">the expiration time of the notification after which it will automatically close. If the value is Zero then the notification will remain open until the user closes it</param>
+    /// <param name="showClose">whether to show the close button</param>
+    /// <param name="onClick">an Action to be run when the notification is clicked</param>
+    /// <param name="onClose">an Action to be run when the notification is closed</param>
+    /// <param name="classes">style classes to apply</param>
+    public async void Show(
+        object content,
+        NotificationType type,
+        TimeSpan? expiration = null,
+        bool showClose = true,
+        Action? onClick = null,
+        Action? onClose = null,
+        string[]? classes = null)
+    {
+        Dispatcher.UIThread.VerifyAccess();
+
+        var notificationControl = new NotificationCard
+        {
+            Content = content,
+            NotificationType = type,
+            ShowClose = showClose
+        };
+
+        // Add style classes if any
+        if (classes is not null)
+        {
+            foreach (var @class in classes)
+            {
+                notificationControl.Classes.Add(@class);
+            }
+        }
+
+        notificationControl.MessageClosed += (sender, _) =>
+        {
+            onClose?.Invoke();
+
+            _items?.Remove(sender);
+        };
+
+        notificationControl.PointerPressed += (_, _) => { onClick?.Invoke(); };
+
+        Dispatcher.UIThread.Post(() =>
+        {
+            _items?.Add(notificationControl);
+
+            if (_items?.OfType<NotificationCard>().Count(i => !i.IsClosing) > MaxItems)
+            {
+                _items.OfType<NotificationCard>().First(i => !i.IsClosing).Close();
+            }
+        });
+
+        if (expiration == TimeSpan.Zero)
+        {
+            return;
+        }
+
+        await Task.Delay(expiration ?? TimeSpan.FromSeconds(3));
+
+        notificationControl.Close();
+    }
+
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+
+        if (change.Property == PositionProperty)
+        {
+            UpdatePseudoClasses(change.GetNewValue<NotificationPosition>());
+        }
+    }
+
+    private void UpdatePseudoClasses(NotificationPosition position)
+    {
+        PseudoClasses.Set(PC_TopLeft, position == NotificationPosition.TopLeft);
+        PseudoClasses.Set(PC_TopRight, position == NotificationPosition.TopRight);
+        PseudoClasses.Set(PC_BottomLeft, position == NotificationPosition.BottomLeft);
+        PseudoClasses.Set(PC_BottomRight, position == NotificationPosition.BottomRight);
+        PseudoClasses.Set(PC_TopCenter, position == NotificationPosition.TopCenter);
+        PseudoClasses.Set(PC_BottomCenter, position == NotificationPosition.BottomCenter);
+    }
+}