Store args in ClassicDesktopStyleApplicationLifetime.

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -47,6 +47,11 @@ namespace Avalonia.Controls.ApplicationLifetimes
         /// <inheritdoc/>
         public event EventHandler<ControlledApplicationLifetimeExitEventArgs> Exit;
 
+        /// <summary>
+        /// Gets the arguments passed to the AppBuilder Start method.
+        /// </summary>
+        public string[] Args { get; set; }
+        
         /// <inheritdoc/>
         public ShutdownMode ShutdownMode { get; set; }
         
@@ -68,9 +73,6 @@ namespace Avalonia.Controls.ApplicationLifetimes
             else if (ShutdownMode == ShutdownMode.OnMainWindowClose && window == MainWindow)
                 Shutdown();
         }
-        
-        
-
 
         public void Shutdown(int exitCode = 0)
         {
@@ -123,7 +125,11 @@ namespace Avalonia
             this T builder, string[] args, ShutdownMode shutdownMode = ShutdownMode.OnLastWindowClose)
             where T : AppBuilderBase<T>, new()
         {
-            var lifetime = new ClassicDesktopStyleApplicationLifetime() {ShutdownMode = shutdownMode};
+            var lifetime = new ClassicDesktopStyleApplicationLifetime()
+            {
+                Args = args,
+                ShutdownMode = shutdownMode
+            };
             builder.SetupWithLifetime(lifetime);
             return lifetime.Start(args);
         }

src/Avalonia.Controls/ApplicationLifetimes/IClassicDesktopStyleApplicationLifetime.cs

@@ -8,6 +8,13 @@ namespace Avalonia.Controls.ApplicationLifetimes
     /// </summary>
     public interface IClassicDesktopStyleApplicationLifetime : IControlledApplicationLifetime
     {
+        /// <summary>
+        /// Gets the arguments passed to the
+        /// <see cref="ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime{T}(T, string[], ShutdownMode)"/>
+        /// method.
+        /// </summary>
+        string[] Args { get; }
+        
         /// <summary>
         /// Gets or sets the <see cref="ShutdownMode"/>. This property indicates whether the application is shutdown explicitly or implicitly. 
         /// If <see cref="ShutdownMode"/> is set to OnExplicitShutdown the application is only closes if Shutdown is called.