diff --git a/samples/ControlCatalog/Pages/DialogsPage.xaml.cs b/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
index fd908a33b6..bed9f4c62a 100644
--- a/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/DialogsPage.xaml.cs
@@ -41,13 +41,17 @@ namespace ControlCatalog.Pages
 
             this.FindControl<Button>("OpenFile").Click += async delegate
             {
+                // Almost guaranteed to exist
+                var fullPath = Assembly.GetEntryAssembly()?.GetModules().FirstOrDefault()?.FullyQualifiedName;
+                var initialFileName = fullPath == null ? null : System.IO.Path.GetFileName(fullPath);
+                var initialDirectory = fullPath == null ? null : System.IO.Path.GetDirectoryName(fullPath);
+
                 var result = await new OpenFileDialog()
                 {
                     Title = "Open file",
                     Filters = GetFilters(),
-                    Directory = lastSelectedDirectory,
-                    // Almost guaranteed to exist
-                    InitialFileName = Assembly.GetEntryAssembly()?.GetModules().FirstOrDefault()?.FullyQualifiedName
+                    Directory = initialDirectory,
+                    InitialFileName = initialFileName
                 }.ShowAsync(GetWindow());
                 results.Items = result;
                 resultsVisible.IsVisible = result?.Any() == true;
@@ -83,7 +87,12 @@ namespace ControlCatalog.Pages
                     Title = "Select folder",
                     Directory = lastSelectedDirectory,
                 }.ShowAsync(GetWindow());
-                lastSelectedDirectory = result;
+
+                if (!string.IsNullOrEmpty(result))
+                {
+                    lastSelectedDirectory = result;
+                }
+
                 results.Items = new [] { result };
                 resultsVisible.IsVisible = result != null;
             };
diff --git a/src/Avalonia.Base/Rendering/ImmediateRenderer.cs b/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
index 2c0298affa..54b2ce5a25 100644
--- a/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
+++ b/src/Avalonia.Base/Rendering/ImmediateRenderer.cs
@@ -277,18 +277,20 @@ namespace Avalonia.Rendering
                 var m = Matrix.CreateTranslation(visual.Bounds.Position);
 
                 var renderTransform = Matrix.Identity;
+                
+                // this should be calculated BEFORE renderTransform
+                if (visual.HasMirrorTransform)
+                {
+                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, visual.Bounds.Width, 0);
+                    renderTransform *= mirrorMatrix;
+                }
 
                 if (visual.RenderTransform != null)
                 {
                     var origin = visual.RenderTransformOrigin.ToPixels(new Size(visual.Bounds.Width, visual.Bounds.Height));
                     var offset = Matrix.CreateTranslation(origin);
-                    renderTransform = (-offset) * visual.RenderTransform.Value * (offset);
-                }
-
-                if (visual.HasMirrorTransform)
-                {
-                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, visual.Bounds.Width, 0);
-                    renderTransform *= mirrorMatrix;
+                    var finalTransform = (-offset) * visual.RenderTransform.Value * (offset);
+                    renderTransform *= finalTransform;
                 }
 
                 m = renderTransform * m;
diff --git a/src/Avalonia.Base/Rendering/SceneGraph/SceneBuilder.cs b/src/Avalonia.Base/Rendering/SceneGraph/SceneBuilder.cs
index 019c3e0e9b..5dc426ab06 100644
--- a/src/Avalonia.Base/Rendering/SceneGraph/SceneBuilder.cs
+++ b/src/Avalonia.Base/Rendering/SceneGraph/SceneBuilder.cs
@@ -188,19 +188,21 @@ namespace Avalonia.Rendering.SceneGraph
 
                 var renderTransform = Matrix.Identity;
 
-                if (visual.RenderTransform != null)
-                {
-                    var origin = visual.RenderTransformOrigin.ToPixels(new Size(visual.Bounds.Width, visual.Bounds.Height));
-                    var offset = Matrix.CreateTranslation(origin);
-                    renderTransform = (-offset) * visual.RenderTransform.Value * (offset);
-                }
-
+                // this should be calculated BEFORE renderTransform
                 if (visual.HasMirrorTransform)
                 {
                     var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, visual.Bounds.Width, 0);
                     renderTransform *= mirrorMatrix;
                 }
 
+                if (visual.RenderTransform != null)
+                {
+                    var origin = visual.RenderTransformOrigin.ToPixels(new Size(visual.Bounds.Width, visual.Bounds.Height));
+                    var offset = Matrix.CreateTranslation(origin);
+                    var finalTransform = (-offset) * visual.RenderTransform.Value * (offset);
+                    renderTransform *= finalTransform;
+                }
+
                 m = renderTransform * m;
 
                 using (contextImpl.BeginUpdate(node))
diff --git a/src/Avalonia.Base/VisualExtensions.cs b/src/Avalonia.Base/VisualExtensions.cs
index 3a3c2693d0..7a5bbb105c 100644
--- a/src/Avalonia.Base/VisualExtensions.cs
+++ b/src/Avalonia.Base/VisualExtensions.cs
@@ -101,6 +101,13 @@ namespace Avalonia
 
             while (v != ancestor)
             {
+                // this should be calculated BEFORE renderTransform
+                if (v.HasMirrorTransform)
+                {
+                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, v.Bounds.Width, 0);
+                    result *= mirrorMatrix;
+                }
+
                 if (v.RenderTransform?.Value != null)
                 {
                     var origin = v.RenderTransformOrigin.ToPixels(v.Bounds.Size);
@@ -110,12 +117,6 @@ namespace Avalonia
                     result *= renderTransform;
                 }
 
-                if (v.HasMirrorTransform)
-                {
-                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, v.Bounds.Width, 0);
-                    result *= mirrorMatrix;
-                }
-
                 var topLeft = v.Bounds.TopLeft;
 
                 if (topLeft != default)
diff --git a/src/Avalonia.Controls/Viewbox.cs b/src/Avalonia.Controls/Viewbox.cs
index 01a41a0157..aabfd3ef18 100644
--- a/src/Avalonia.Controls/Viewbox.cs
+++ b/src/Avalonia.Controls/Viewbox.cs
@@ -168,6 +168,8 @@ namespace Avalonia.Controls
 
                         if (_child is not null)
                             VisualChildren.Add(_child);
+
+                        InvalidateMeasure();
                     }
                 }
             }
diff --git a/src/Avalonia.X11/NativeDialogs/Gtk.cs b/src/Avalonia.X11/NativeDialogs/Gtk.cs
index a0f146afa8..73e6a2d6a4 100644
--- a/src/Avalonia.X11/NativeDialogs/Gtk.cs
+++ b/src/Avalonia.X11/NativeDialogs/Gtk.cs
@@ -195,7 +195,10 @@ namespace Avalonia.X11.NativeDialogs
 
         [DllImport(GtkName)]
         public static extern void gtk_file_chooser_set_current_name(IntPtr chooser, Utf8Buffer file);
-        
+
+        [DllImport(GtkName)]
+        public static extern void gtk_file_chooser_set_current_folder(IntPtr chooser, Utf8Buffer file);
+
         [DllImport(GtkName)]
         public static extern IntPtr gtk_file_filter_new();
         
diff --git a/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs b/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs
index 1a6514eb03..9539f024b7 100644
--- a/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs
+++ b/src/Avalonia.X11/NativeDialogs/GtkNativeFileDialogs.cs
@@ -15,8 +15,9 @@ namespace Avalonia.X11.NativeDialogs
     class GtkSystemDialog : ISystemDialogImpl
     {
         private Task<bool> _initialized;
-        private unsafe  Task<string[]> ShowDialog(string title, IWindowImpl parent, GtkFileChooserAction action,
-            bool multiSelect, string initialFileName, IEnumerable<FileDialogFilter> filters, string defaultExtension, bool overwritePrompt)
+
+        private unsafe Task<string[]> ShowDialog(string title, IWindowImpl parent, GtkFileChooserAction action,
+            bool multiSelect, string initialDirectory, string initialFileName, IEnumerable<FileDialogFilter> filters, string defaultExtension, bool overwritePrompt)
         {
             IntPtr dlg;
             using (var name = new Utf8Buffer(title))
@@ -44,7 +45,7 @@ namespace Avalonia.X11.NativeDialogs
                     filtersDic[filter] = f;
                     using (var b = new Utf8Buffer(f.Name))
                         gtk_file_filter_set_name(filter, b);
-                    
+
                     foreach (var e in f.Extensions)
                         using (var b = new Utf8Buffer("*." + e))
                             gtk_file_filter_add_pattern(filter, b);
@@ -100,17 +101,32 @@ namespace Avalonia.X11.NativeDialogs
                 gtk_dialog_add_button(dlg, open, GtkResponseType.Accept);
             using (var open = new Utf8Buffer("Cancel"))
                 gtk_dialog_add_button(dlg, open, GtkResponseType.Cancel);
+
+            if (initialDirectory != null)
+            {
+                using var dir = new Utf8Buffer(initialDirectory);
+                gtk_file_chooser_set_current_folder(dlg, dir);
+            }
+
             if (initialFileName != null)
-                using (var fn = new Utf8Buffer(initialFileName))
+            {
+                // gtk_file_chooser_set_filename() expects full path
+                using var fn = action == GtkFileChooserAction.Open
+                    ? new Utf8Buffer(Path.Combine(initialDirectory ?? "", initialFileName))
+                    : new Utf8Buffer(initialFileName);
+
+                if (action == GtkFileChooserAction.Save)
                 {
-                    if (action == GtkFileChooserAction.Save)
-                        gtk_file_chooser_set_current_name(dlg, fn);
-                    else
-                        gtk_file_chooser_set_filename(dlg, fn);
+                    gtk_file_chooser_set_current_name(dlg, fn);
                 }
+                else
+                {
+                    gtk_file_chooser_set_filename(dlg, fn);
+                }
+            }
 
             gtk_file_chooser_set_do_overwrite_confirmation(dlg, overwritePrompt);
-            
+
             gtk_window_present(dlg);
             return tcs.Task;
         }
@@ -144,13 +160,15 @@ namespace Avalonia.X11.NativeDialogs
 
             var platformImpl = parent?.PlatformImpl;
 
-            return await await RunOnGlibThread(
-                () => ShowDialog(dialog.Title, platformImpl,
-                    dialog is OpenFileDialog ? GtkFileChooserAction.Open : GtkFileChooserAction.Save,
-                    (dialog as OpenFileDialog)?.AllowMultiple ?? false,
-                    Path.Combine(string.IsNullOrEmpty(dialog.Directory) ? "" : dialog.Directory,
-                        string.IsNullOrEmpty(dialog.InitialFileName) ? "" : dialog.InitialFileName), dialog.Filters,
-                    (dialog as SaveFileDialog)?.DefaultExtension, (dialog as SaveFileDialog)?.ShowOverwritePrompt ?? false));
+            return await await RunOnGlibThread(() => ShowDialog(
+                dialog.Title, platformImpl,
+                dialog is OpenFileDialog ? GtkFileChooserAction.Open : GtkFileChooserAction.Save,
+                (dialog as OpenFileDialog)?.AllowMultiple ?? false,
+                dialog.Directory,
+                dialog.InitialFileName,
+                dialog.Filters,
+                (dialog as SaveFileDialog)?.DefaultExtension,
+                (dialog as SaveFileDialog)?.ShowOverwritePrompt ?? false));
         }
 
         public async Task<string> ShowFolderDialogAsync(OpenFolderDialog dialog, Window parent)
@@ -161,12 +179,20 @@ namespace Avalonia.X11.NativeDialogs
 
             return await await RunOnGlibThread(async () =>
             {
-                var res = await ShowDialog(dialog.Title, platformImpl,
-                    GtkFileChooserAction.SelectFolder, false, dialog.Directory, null, null, false);
+                var res = await ShowDialog(
+                    dialog.Title,
+                    platformImpl,GtkFileChooserAction.SelectFolder,
+                    false,
+                    dialog.Directory,
+                    null,
+                    null,
+                    null,
+                    false);
+
                 return res?.FirstOrDefault();
             });
         }
-        
+
         async Task EnsureInitialized()
         {
             if (_initialized == null) _initialized = StartGtk();
@@ -174,7 +200,7 @@ namespace Avalonia.X11.NativeDialogs
             if (!(await _initialized))
                 throw new Exception("Unable to initialize GTK on separate thread");
         }
-        
+
         void UpdateParent(IntPtr chooser, IWindowImpl parentWindow)
         {
             var xid = parentWindow.Handle.Handle;
diff --git a/tests/Avalonia.Controls.UnitTests/ViewboxTests.cs b/tests/Avalonia.Controls.UnitTests/ViewboxTests.cs
index 3cebe142b6..4ffd314857 100644
--- a/tests/Avalonia.Controls.UnitTests/ViewboxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/ViewboxTests.cs
@@ -181,6 +181,32 @@ namespace Avalonia.Controls.UnitTests
             Assert.Null(child.GetLogicalParent());
         }
 
+        [Fact]
+        public void Changing_Child_Should_Invalidate_Layout()
+        {
+            var target = new Viewbox();
+
+            target.Child = new Canvas
+            {
+                Width = 100,
+                Height = 100,
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+            Assert.Equal(new Size(100, 100), target.DesiredSize);
+
+            target.Child = new Canvas
+            {
+                Width = 200,
+                Height = 200,
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+            Assert.Equal(new Size(200, 200), target.DesiredSize);
+        }
+
         private bool TryGetScale(Viewbox viewbox, out Vector scale)
         {
             if (viewbox.InternalTransform is null)