Added interface and implementation for application exiting. Will automatically close all windows when called.

src/Perspex.Application/Application.cs

@@ -32,7 +32,7 @@ namespace Perspex
     /// method.
     /// - Tracks the lifetime of the application.
     /// </remarks>
-    public class Application : IGlobalDataTemplates, IGlobalStyles, IStyleRoot
+    public class Application : IGlobalDataTemplates, IGlobalStyles, IStyleRoot, IApplicationLifecycle
     {
         static Action _platformInitializationCallback;
 
@@ -60,6 +60,7 @@ namespace Perspex
             }
 
             PerspexLocator.CurrentMutable.BindToSelf(this);
+            OnExit += OnExiting;
         }
 
         /// <summary>
@@ -146,10 +147,35 @@ namespace Perspex
         public void Run(ICloseable closable)
         {
             var source = new CancellationTokenSource();
+            closable.Closed += OnExiting;
             closable.Closed += (s, e) => source.Cancel();
             Dispatcher.UIThread.MainLoop(source.Token);
         }
 
+        /// <summary>
+        /// Exits the application
+        /// </summary>
+        public void Exit()
+        {
+            OnExit?.Invoke(this, EventArgs.Empty);
+        }
+        
+        /// <summary>
+        /// Sent when the application is exiting.
+        /// </summary>
+        public event EventHandler OnExit;
+
+
+        /// <summary>
+        /// Called when the application is exiting.
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        protected virtual void OnExiting(object sender, EventArgs e)
+        {
+
+        }
+
         /// <summary>
         /// Register's the services needed by Perspex.
         /// </summary>
@@ -168,7 +194,8 @@ namespace Perspex
                 .Bind<IKeyboardNavigationHandler>().ToTransient<KeyboardNavigationHandler>()
                 .Bind<IStyler>().ToConstant(_styler)
                 .Bind<ILayoutManager>().ToTransient<LayoutManager>()
-                .Bind<IRenderQueueManager>().ToTransient<RenderQueueManager>();
+                .Bind<IRenderQueueManager>().ToTransient<RenderQueueManager>()
+                .Bind<IApplicationLifecycle>().ToConstant(this);
         }
 
         /// <summary>

src/Perspex.Controls/IApplicationLifecycle.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Perspex.Controls
+{
+    /// <summary>
+    /// Sends events about the application lifecycle.
+    /// </summary>
+    public interface IApplicationLifecycle
+    {
+        /// <summary>
+        /// Sent when the application is exiting.
+        /// </summary>
+        event EventHandler OnExit;
+
+        /// <summary>
+        /// Exits the application.
+        /// </summary>
+        void Exit();
+    }
+}

src/Perspex.Controls/Perspex.Controls.csproj

@@ -50,6 +50,7 @@
     <Compile Include="Generators\ItemContainer.cs" />
     <Compile Include="Generators\TreeContainerIndex.cs" />
     <Compile Include="HotkeyManager.cs" />
+    <Compile Include="IApplicationLifecycle.cs" />
     <Compile Include="INameScope.cs" />
     <Compile Include="IPseudoClasses.cs" />
     <Compile Include="DropDownItem.cs" />

src/Perspex.Controls/TopLevel.cs

@@ -48,6 +48,7 @@ namespace Perspex.Controls
         private readonly IInputManager _inputManager;
         private readonly IAccessKeyHandler _accessKeyHandler;
         private readonly IKeyboardNavigationHandler _keyboardNavigationHandler;
+        private readonly IApplicationLifecycle _applicationLifecycle;
         private Size _clientSize;
         private bool _isActive;
 
@@ -92,6 +93,7 @@ namespace Perspex.Controls
             _inputManager = TryGetService<IInputManager>(dependencyResolver);
             _keyboardNavigationHandler = TryGetService<IKeyboardNavigationHandler>(dependencyResolver);
             _renderQueueManager = TryGetService<IRenderQueueManager>(dependencyResolver);
+            _applicationLifecycle = TryGetService<IApplicationLifecycle>(dependencyResolver);
             (TryGetService<ITopLevelRenderer>(dependencyResolver) ?? new DefaultTopLevelRenderer()).Attach(this);
 
             PlatformImpl.SetInputRoot(this);
@@ -112,6 +114,7 @@ namespace Perspex.Controls
                 .Select(
                     x => (x as InputElement)?.GetObservable(CursorProperty) ?? Observable.Empty<Cursor>())
                 .Switch().Subscribe(cursor => PlatformImpl.SetCursor(cursor?.PlatformCursor));
+            _applicationLifecycle.OnExit += HandleApplicationExiting;
         }
 
         /// <summary>
@@ -347,6 +350,20 @@ namespace Perspex.Controls
         private void HandleClosed()
         {
             Closed?.Invoke(this, EventArgs.Empty);
+            _applicationLifecycle.OnExit -= OnApplicationExiting;
+        }
+
+        private void OnApplicationExiting(object sender, EventArgs args)
+        {
+
+        }
+
+        /// <summary>
+        /// Handles the application exiting, either from the last window closing, or a call to <see cref="IApplicationLifecycle.Exit"/>.
+        /// </summary>
+        protected virtual void HandleApplicationExiting()
+        {
+
         }
 
         /// <summary>

src/Perspex.Controls/Window.cs

@@ -156,6 +156,12 @@ namespace Perspex.Controls
             PlatformImpl.Dispose();
         }
 
+        protected override void HandleApplicationExiting()
+        {
+            base.HandleApplicationExiting();
+            Close();
+        }
+
         /// <summary>
         /// Closes a dialog window with the specified result.
         /// </summary>