Added a "script" to load all control catalog pages in headless mode

samples/ControlCatalog.NetCore/Program.cs

@@ -2,8 +2,12 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
+using System.Threading.Tasks;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Headless;
+using Avalonia.LogicalTree;
 using Avalonia.Skia;
 using Avalonia.ReactiveUI;
 using Avalonia.Threading;
@@ -37,6 +41,48 @@ namespace ControlCatalog.NetCore
             {
                 return builder.StartWithHeadlessVncPlatform(null, 5901, args, ShutdownMode.OnMainWindowClose);
             }
+            else if (args.Contains("--full-headless"))
+            {
+                return builder
+                    .UseHeadless(true)
+                    .AfterSetup(_ =>
+                    {
+                        DispatcherTimer.RunOnce(async () =>
+                        {
+                            var window = ((IClassicDesktopStyleApplicationLifetime)Application.Current.ApplicationLifetime)
+                                .MainWindow;
+                            var tc = window.GetLogicalDescendants().OfType<TabControl>().First();
+                            foreach (var page in tc.Items.Cast<TabItem>().ToList())
+                            {
+                                // Skip DatePicker because of some layout bug in grid
+                                if (page.Header.ToString() == "DatePicker")
+                                    continue;
+                                Console.WriteLine("Selecting " + page.Header);
+                                tc.SelectedItem = page;
+                                await Task.Delay(500);
+                            }
+                            Console.WriteLine("Selecting the first page");
+                            tc.SelectedItem = tc.Items.OfType<object>().First();
+                            await Task.Delay(500);
+                            Console.WriteLine("Clicked through all pages, triggering GC");
+                            for (var c = 0; c < 3; c++)
+                            {
+                                GC.Collect(2, GCCollectionMode.Forced);
+                                await Task.Delay(500);
+                            }
+
+                            void FormatMem(string metric, long bytes)
+                            {
+                                Console.WriteLine(metric + ": " + bytes / 1024 / 1024 + "MB");
+                            }
+
+                            FormatMem("GC allocated bytes", GC.GetTotalMemory(true));
+                            FormatMem("WorkingSet64", Process.GetCurrentProcess().WorkingSet64);
+
+                        }, TimeSpan.FromSeconds(1));
+                    })
+                    .StartWithClassicDesktopLifetime(args);
+            }
             else
                 return builder.StartWithClassicDesktopLifetime(args);
         }

src/Avalonia.Headless/HeadlessWindowImpl.cs

@@ -118,8 +118,12 @@ namespace Avalonia.Headless
 
         void DoResize(Size clientSize)
         {
-            ClientSize = clientSize;
-            Resized?.Invoke(clientSize);
+            // Uncomment this check and experience a weird bug in layout engine
+            if (ClientSize != clientSize)
+            {
+                ClientSize = clientSize;
+                Resized?.Invoke(clientSize);
+            }
         }
 
         public void SetMinMaxSize(Size minSize, Size maxSize)