Merge branch 'master' into cleanup-platformsupport

native/Avalonia.Native/src/OSX/AvnWindow.mm

@@ -33,6 +33,7 @@
     bool _isEnabled;
     bool _canBecomeKeyWindow;
     bool _isExtended;
+    bool _isTransitioningToFullScreen;
     AvnMenu* _menu;
 }
 
@@ -175,6 +176,7 @@
     [self setBackgroundColor: [NSColor clearColor]];
 
     _isExtended = false;
+    _isTransitioningToFullScreen = false;
 
     if(self.isDialog)
     {
@@ -282,6 +284,14 @@
 - (void)windowDidBecomeKey:(NSNotification *_Nonnull)notification
 {
     _parent->BringToFront();
+    
+    dispatch_async(dispatch_get_main_queue(), ^{
+        @try {
+        [self invalidateShadow];
+        }
+        @finally{
+        }
+    });
 }
 
 - (void)windowDidMiniaturize:(NSNotification *_Nonnull)notification
@@ -349,6 +359,7 @@
 
 - (void)windowWillEnterFullScreen:(NSNotification *_Nonnull)notification
 {
+    _isTransitioningToFullScreen = true;
     auto parent = dynamic_cast<IWindowStateChanged*>(_parent.operator->());
 
     if(parent != nullptr)
@@ -359,6 +370,7 @@
 
 - (void)windowDidEnterFullScreen:(NSNotification *_Nonnull)notification
 {
+    _isTransitioningToFullScreen = false;
     auto parent = dynamic_cast<IWindowStateChanged*>(_parent.operator->());
 
     if(parent != nullptr)
@@ -441,7 +453,10 @@
                     _parent->BaseEvents->RawMouseEvent(NonClientLeftButtonDown, static_cast<uint32>([event timestamp] * 1000), AvnInputModifiersNone, point, delta);
                 }
                 
-                _parent->BringToFront();
+                if(!_isTransitioningToFullScreen)
+                {
+                    _parent->BringToFront();
+                }
             }
             break;
 

native/Avalonia.Native/src/OSX/PopupImpl.mm

@@ -26,17 +26,13 @@ private:
     PopupImpl(IAvnWindowEvents* events, IAvnGlContext* gl) : WindowBaseImpl(events, gl)
     {
         WindowEvents = events;
+        [Window setLevel:NSPopUpMenuWindowLevel];
     }
 protected:
     virtual NSWindowStyleMask GetStyle() override
     {
         return NSWindowStyleMaskBorderless;
     }
-    
-    virtual void OnInitialiseNSWindow () override
-    {
-        [Window setLevel:NSPopUpMenuWindowLevel];
-    }
 
 public:
     virtual bool ShouldTakeFocusOnShow() override

native/Avalonia.Native/src/OSX/WindowBaseImpl.h

@@ -106,13 +106,10 @@ protected:
     virtual NSWindowStyleMask GetStyle();
 
     void UpdateStyle();
-                           
-    virtual void OnInitialiseNSWindow ();
 
 private:
     void CreateNSWindow (bool isDialog);
     void CleanNSWindow ();
-    void InitialiseNSWindow ();
 
     NSCursor *cursor;
     ComPtr<IAvnGlContext> _glContext;

native/Avalonia.Native/src/OSX/WindowBaseImpl.mm

@@ -39,7 +39,16 @@ WindowBaseImpl::WindowBaseImpl(IAvnWindowBaseEvents *events, IAvnGlContext *gl,
     lastMenu = nullptr;
     
     CreateNSWindow(usePanel);
-    InitialiseNSWindow();
+    
+    [Window setContentView:StandardContainer];
+    [Window setStyleMask:NSWindowStyleMaskBorderless];
+    [Window setBackingType:NSBackingStoreBuffered];
+
+    [Window setContentMinSize:lastMinSize];
+    [Window setContentMaxSize:lastMaxSize];
+
+    [Window setOpaque:false];
+    [Window setHasShadow:true];
 }
 
 HRESULT WindowBaseImpl::ObtainNSViewHandle(void **ret) {
@@ -90,8 +99,8 @@ HRESULT WindowBaseImpl::Show(bool activate, bool isDialog) {
     START_COM_CALL;
 
     @autoreleasepool {
-        InitialiseNSWindow();
-
+        [Window setContentSize:lastSize];
+        
         if(hasPosition)
         {
             SetPosition(lastPositionSet);
@@ -101,6 +110,8 @@ HRESULT WindowBaseImpl::Show(bool activate, bool isDialog) {
         }
 
         UpdateStyle();
+        
+        [Window invalidateShadow];
 
         if (ShouldTakeFocusOnShow() && activate) {
             [Window orderFront:Window];
@@ -292,8 +303,7 @@ HRESULT WindowBaseImpl::Resize(double x, double y, AvnPlatformResizeReason reaso
             if (!_shown) {
                 BaseEvents->Resized(AvnSize{x, y}, reason);
             }
-
-            if(Window != nullptr) {
+            else if(Window != nullptr) {
                 [Window setContentSize:lastSize];
                 [Window invalidateShadow];
             }
@@ -569,38 +579,6 @@ void WindowBaseImpl::CreateNSWindow(bool isDialog) {
     }
 }
 
-void WindowBaseImpl::OnInitialiseNSWindow()
-{
-    
-}
-
-void WindowBaseImpl::InitialiseNSWindow() {
-    if(Window != nullptr) {
-        [Window setContentView:StandardContainer];
-        [Window setStyleMask:NSWindowStyleMaskBorderless];
-        [Window setBackingType:NSBackingStoreBuffered];
-
-        [Window setContentSize:lastSize];
-        [Window setContentMinSize:lastMinSize];
-        [Window setContentMaxSize:lastMaxSize];
-
-        [Window setOpaque:false];
-        
-        [Window setHasShadow:true];
-        [Window invalidateShadow];
-
-        if (lastMenu != nullptr) {
-            [GetWindowProtocol() applyMenu:lastMenu];
-
-            if ([Window isKeyWindow]) {
-                [GetWindowProtocol() showWindowMenuWithAppMenu];
-            }
-        }
-        
-        OnInitialiseNSWindow();
-    }
-}
-
 id <AvnWindowProtocol> WindowBaseImpl::GetWindowProtocol() {
     if(Window == nullptr)
     {

native/Avalonia.Native/src/OSX/WindowImpl.h

@@ -93,8 +93,6 @@ BEGIN_INTERFACE_MAP()
 
     virtual bool IsDialog() override;
     
-    virtual void OnInitialiseNSWindow() override;
-    
     virtual void BringToFront () override;
     
     bool CanBecomeKeyWindow ();
@@ -103,6 +101,7 @@ protected:
     virtual NSWindowStyleMask GetStyle() override;
 
 private:
+    void OnInitialiseNSWindow();
     NSString *_lastTitle;
 };
 

native/Avalonia.Native/src/OSX/WindowImpl.mm

@@ -24,6 +24,8 @@ WindowImpl::WindowImpl(IAvnWindowEvents *events, IAvnGlContext *gl) : WindowBase
     _lastTitle = @"";
     _parent = nullptr;
     WindowEvents = events;
+    
+    OnInitialiseNSWindow();
 }
 
 void WindowImpl::HideOrShowTrafficLights() {
@@ -32,15 +34,16 @@ void WindowImpl::HideOrShowTrafficLights() {
     }
 
     bool wantsChrome = (_extendClientHints & AvnSystemChrome) || (_extendClientHints & AvnPreferSystemChrome);
-    bool hasTrafficLights = _isClientAreaExtended ? !wantsChrome : _decorations != SystemDecorationsFull;
+    bool hasTrafficLights = _isClientAreaExtended ? wantsChrome : _decorations == SystemDecorationsFull;
     
-    [[Window standardWindowButton:NSWindowCloseButton] setHidden:hasTrafficLights];
-    [[Window standardWindowButton:NSWindowMiniaturizeButton] setHidden:hasTrafficLights];
-    [[Window standardWindowButton:NSWindowZoomButton] setHidden:hasTrafficLights];
+    [[Window standardWindowButton:NSWindowCloseButton] setHidden:!hasTrafficLights];
+    [[Window standardWindowButton:NSWindowMiniaturizeButton] setHidden:!hasTrafficLights];
+    [[Window standardWindowButton:NSWindowZoomButton] setHidden:!hasTrafficLights];
 }
 
 void WindowImpl::OnInitialiseNSWindow(){
     [GetWindowProtocol() setCanBecomeKeyWindow:true];
+    
     [Window disableCursorRects];
     [Window setTabbingMode:NSWindowTabbingModeDisallowed];
     [Window setCollectionBehavior:NSWindowCollectionBehaviorFullScreenPrimary];
@@ -52,11 +55,6 @@ void WindowImpl::OnInitialiseNSWindow(){
         [GetWindowProtocol() setIsExtended:true];
         SetExtendClientArea(true);
     }
-    
-    if(_parent != nullptr)
-    {
-        SetParent(_parent);
-    }
 }
 
 HRESULT WindowImpl::Show(bool activate, bool isDialog) {

native/Avalonia.Native/src/OSX/app.mm

@@ -82,6 +82,17 @@ ComPtr<IAvnApplicationEvents> _events;
         _isHandlingSendEvent = oldHandling;
     }
 }
+
+// This is needed for certain embedded controls DO NOT REMOVE..
+- (BOOL) isHandlingSendEvent
+{
+    return _isHandlingSendEvent;
+}
+
+- (void)setHandlingSendEvent:(BOOL)handlingSendEvent
+{
+    _isHandlingSendEvent = handlingSendEvent;
+}
 @end
 
 extern void InitializeAvnApp(IAvnApplicationEvents* events)

samples/ControlCatalog/Converter/MathSubtractConverter.cs

@@ -6,12 +6,16 @@ namespace ControlCatalog.Converter;
 
 public class MathSubtractConverter : IValueConverter
 {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
     {
-        return (double)value - (double)parameter;
+        if (value is double dv && parameter is double dp)
+        {
+            return dv - dp;
+        }
+        return double.NaN;
     }
 
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
     {
         throw new NotSupportedException();
     }

samples/ControlCatalog/DecoratedWindow.xaml.cs

@@ -15,7 +15,7 @@ namespace ControlCatalog
 
         void SetupSide(string name, StandardCursorType cursor, WindowEdge edge)
         {
-            var ctl = this.FindControl<Control>(name);
+            var ctl = this.Get<Control>(name);
             ctl.Cursor = new Cursor(cursor);
             ctl.PointerPressed += (i, e) =>
             {
@@ -26,7 +26,7 @@ namespace ControlCatalog
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);
-            this.FindControl<Control>("TitleBar").PointerPressed += (i, e) =>
+            this.Get<Control>("TitleBar").PointerPressed += (i, e) =>
             {
                 PlatformImpl?.BeginMoveDrag(e);
             };
@@ -38,12 +38,12 @@ namespace ControlCatalog
             SetupSide("TopRight", StandardCursorType.TopRightCorner, WindowEdge.NorthEast);
             SetupSide("BottomLeft", StandardCursorType.BottomLeftCorner, WindowEdge.SouthWest);
             SetupSide("BottomRight", StandardCursorType.BottomRightCorner, WindowEdge.SouthEast);
-            this.FindControl<Button>("MinimizeButton").Click += delegate { this.WindowState = WindowState.Minimized; };
-            this.FindControl<Button>("MaximizeButton").Click += delegate
+            this.Get<Button>("MinimizeButton").Click += delegate { this.WindowState = WindowState.Minimized; };
+            this.Get<Button>("MaximizeButton").Click += delegate
             {
                 WindowState = WindowState == WindowState.Maximized ? WindowState.Normal : WindowState.Maximized;
             };
-            this.FindControl<Button>("CloseButton").Click += delegate
+            this.Get<Button>("CloseButton").Click += delegate
             {
                 Close();
             };

samples/ControlCatalog/MainView.xaml.cs

@@ -18,9 +18,9 @@ namespace ControlCatalog
         {
             AvaloniaXamlLoader.Load(this);
 
-            var sideBar = this.FindControl<TabControl>("Sidebar");
+            var sideBar = this.Get<TabControl>("Sidebar");
 
-            if (AvaloniaLocator.Current.GetService<IRuntimePlatform>().GetRuntimeInfo().IsDesktop)
+            if (AvaloniaLocator.Current?.GetService<IRuntimePlatform>()?.GetRuntimeInfo().IsDesktop == true)
             {
                 IList tabItems = ((IList)sideBar.Items);
                 tabItems.Add(new TabItem()
@@ -36,7 +36,7 @@ namespace ControlCatalog
 
             }
 
-            var themes = this.Find<ComboBox>("Themes");
+            var themes = this.Get<ComboBox>("Themes");
             themes.SelectionChanged += (sender, e) =>
             {
                 if (themes.SelectedItem is CatalogTheme theme)
@@ -80,7 +80,7 @@ namespace ControlCatalog
                 }
             };
 
-            var flowDirections = this.Find<ComboBox>("FlowDirection");
+            var flowDirections = this.Get<ComboBox>("FlowDirection");
             flowDirections.SelectionChanged += (sender, e) =>
             {
                 if (flowDirections.SelectedItem is FlowDirection flowDirection)
@@ -89,7 +89,7 @@ namespace ControlCatalog
                 }
             };
 
-            var decorations = this.Find<ComboBox>("Decorations");
+            var decorations = this.Get<ComboBox>("Decorations");
             decorations.SelectionChanged += (sender, e) =>
             {
                 if (VisualRoot is Window window
@@ -99,8 +99,8 @@ namespace ControlCatalog
                 }
             };
 
-            var transparencyLevels = this.Find<ComboBox>("TransparencyLevels");
-            IDisposable backgroundSetter = null, paneBackgroundSetter = null;
+            var transparencyLevels = this.Get<ComboBox>("TransparencyLevels");
+            IDisposable? backgroundSetter = null, paneBackgroundSetter = null;
             transparencyLevels.SelectionChanged += (sender, e) =>
             {
                 backgroundSetter?.Dispose();
@@ -118,7 +118,7 @@ namespace ControlCatalog
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTree(e);
-            var decorations = this.Find<ComboBox>("Decorations");
+            var decorations = this.Get<ComboBox>("Decorations");
             if (VisualRoot is Window window)
                 decorations.SelectedIndex = (int)window.SystemDecorations;
         }

samples/ControlCatalog/MainWindow.xaml.cs

@@ -12,7 +12,7 @@ namespace ControlCatalog
     public class MainWindow : Window
     {
         private WindowNotificationManager _notificationArea;
-        private NativeMenu _recentMenu;
+        private NativeMenu? _recentMenu;
 
         public MainWindow()
         {
@@ -28,9 +28,7 @@ namespace ControlCatalog
             };
 
             DataContext = new MainWindowViewModel(_notificationArea);
-            _recentMenu = ((NativeMenu.GetMenu(this).Items[0] as NativeMenuItem).Menu.Items[2] as NativeMenuItem).Menu;
-
-            ExtendClientAreaChromeHints = Avalonia.Platform.ExtendClientAreaChromeHints.OSXThickTitleBar;
+            _recentMenu = ((NativeMenu.GetMenu(this)?.Items[0] as NativeMenuItem)?.Menu?.Items[2] as NativeMenuItem)?.Menu;
         }
 
         public static string MenuQuitHeader => RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ? "Quit Avalonia" : "E_xit";
@@ -41,7 +39,7 @@ namespace ControlCatalog
 
         public void OnOpenClicked(object sender, EventArgs args)
         {
-            _recentMenu.Items.Insert(0, new NativeMenuItem("Item " + (_recentMenu.Items.Count + 1)));
+            _recentMenu?.Items.Insert(0, new NativeMenuItem("Item " + (_recentMenu.Items.Count + 1)));
         }
 
         public void OnCloseClicked(object sender, EventArgs args)

samples/ControlCatalog/Models/Countries.cs

@@ -237,7 +237,7 @@ namespace ControlCatalog.Models
             yield return new Country("Zimbabwe", "SUB-SAHARAN AFRICA", 12236805, 390580, 31.3, 0, 0, 67.69, 1900, 90.7, 26.8, 28.01, 21.84);
         }
 
-        static IReadOnlyList<Country> _all;
+        static IReadOnlyList<Country>? _all;
 
         public static IReadOnlyList<Country> All
         {
@@ -253,4 +253,4 @@ namespace ControlCatalog.Models
 
         }
     }
-}
+}

samples/ControlCatalog/Models/GDPValueConverter.cs

@@ -14,7 +14,7 @@ namespace ControlCatalog.Models
 {
     public class GDPValueConverter : IValueConverter
     {
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
             if (value is int gdp)
             {
@@ -29,7 +29,7 @@ namespace ControlCatalog.Models
             return value;
         }
 
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
         {
             throw new NotImplementedException();
         }

samples/ControlCatalog/Models/Person.cs

@@ -13,8 +13,8 @@ namespace ControlCatalog.Models
 {
     public class Person : INotifyDataErrorInfo, INotifyPropertyChanged
     {
-        string _firstName;
-        string _lastName;
+        string _firstName = string.Empty;
+        string _lastName = string.Empty;
         bool _isBanned;
         private int _age;
 
@@ -76,7 +76,7 @@ namespace ControlCatalog.Models
 
         Dictionary<string, List<string>> _errorLookup = new Dictionary<string, List<string>>();
 
-        void SetError(string propertyName, string error)
+        void SetError(string propertyName, string? error)
         {
             if (string.IsNullOrEmpty(error))
             {
@@ -88,11 +88,11 @@ namespace ControlCatalog.Models
                 if (_errorLookup.TryGetValue(propertyName, out List<string> errorList))
                 {
                     errorList.Clear();
-                    errorList.Add(error);
+                    errorList.Add(error!);
                 }
                 else
                 {
-                    var errors = new List<string> { error };
+                    var errors = new List<string> { error! };
                     _errorLookup.Add(propertyName, errors);
                 }
 
@@ -102,8 +102,8 @@ namespace ControlCatalog.Models
 
         public bool HasErrors => _errorLookup.Count > 0;
 
-        public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
-        public event PropertyChangedEventHandler PropertyChanged;
+        public event EventHandler<DataErrorsChangedEventArgs>? ErrorsChanged;
+        public event PropertyChangedEventHandler? PropertyChanged;
 
         void OnErrorsChanged(string propertyName)
         {
@@ -114,7 +114,7 @@ namespace ControlCatalog.Models
             PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
         }
 
-        public IEnumerable GetErrors(string propertyName)
+        public IEnumerable? GetErrors(string propertyName)
         {
             if (_errorLookup.TryGetValue(propertyName, out List<string> errorList))
                 return errorList;

samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml.cs

@@ -126,13 +126,13 @@ namespace ControlCatalog.Pages
             binding.Bindings.Add(new Binding("Name"));
             binding.Bindings.Add(new Binding("Abbreviation"));
 
-            var multibindingBox = this.FindControl<AutoCompleteBox>("MultiBindingBox");
+            var multibindingBox = this.Get<AutoCompleteBox>("MultiBindingBox");
             multibindingBox.ValueMemberBinding = binding;
 
-            var asyncBox = this.FindControl<AutoCompleteBox>("AsyncBox");
+            var asyncBox = this.Get<AutoCompleteBox>("AsyncBox");
             asyncBox.AsyncPopulator = PopulateAsync;
 
-            var customAutocompleteBox = this.FindControl<AutoCompleteBox>("CustomAutocompleteBox");
+            var customAutocompleteBox = this.Get<AutoCompleteBox>("CustomAutocompleteBox");
             customAutocompleteBox.Items = Sentences.SelectMany(x => x);
             customAutocompleteBox.TextFilter = LastWordContains;
             customAutocompleteBox.TextSelector = AppendWord;
@@ -144,11 +144,12 @@ namespace ControlCatalog.Pages
                     .OfType<AutoCompleteBox>();
         }
 
-        private bool StringContains(string str, string query)
+        private bool StringContains(string str, string? query)
         {
+            if (query == null) return false;
             return str.IndexOf(query, StringComparison.OrdinalIgnoreCase) >= 0;
         }
-        private async Task<IEnumerable<object>> PopulateAsync(string searchText, CancellationToken cancellationToken)
+        private async Task<IEnumerable<object>> PopulateAsync(string? searchText, CancellationToken cancellationToken)
         {
             await Task.Delay(TimeSpan.FromSeconds(1.5), cancellationToken);
 
@@ -157,14 +158,14 @@ namespace ControlCatalog.Pages
                       .ToList();
         }
 
-        private bool LastWordContains(string searchText, string item)
+        private bool LastWordContains(string? searchText, string? item)
         {
-            var words = searchText.Split(' ');
+            var words = searchText?.Split(' ') ?? Array.Empty<string>();
             var options = Sentences.Select(x => x.First).ToArray();
             for (var i = 0; i < words.Length; ++i)
             {
                 var word = words[i];
-                for (var j = 0; j < options.Length; ++j)
+                for (var j = 0; word is { } && j < options.Length; ++j)
                 {
                     var option = options[j];
                     if (option == null)
@@ -183,14 +184,18 @@ namespace ControlCatalog.Pages
 
             return options.Any(x => x != null && x.Value == item);
         }
-        private string AppendWord(string text, string item)
+        private string AppendWord(string? text, string? item)
         {
-            string[] parts = text.Split(' ');
-            if (parts.Length == 0)
-                return item;
+            if (item is { })
+            {
+                string[] parts = text?.Split(' ') ?? Array.Empty<string>();
+                if (parts.Length == 0)
+                    return item;
 
-            parts[parts.Length - 1] = item;
-            return string.Join(" ", parts);
+                parts[parts.Length - 1] = item;
+                return string.Join(" ", parts);
+            }
+            return string.Empty;
         }
 
         private void InitializeComponent()

samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml.cs

@@ -23,7 +23,7 @@ namespace ControlCatalog.Pages
             var spinner = (ButtonSpinner)sender;
             var txtBox = (TextBlock)spinner.Content;
 
-            int value = Array.IndexOf(_mountains, txtBox.Text);
+            int value = Array.IndexOf(_mountains, txtBox?.Text);
             if (e.Direction == SpinDirection.Increase)
                 value++;
             else

samples/ControlCatalog/Pages/ButtonsPage.xaml.cs

@@ -11,7 +11,7 @@ namespace ControlCatalog.Pages
         {
             InitializeComponent();
 
-            this.FindControl<RepeatButton>("RepeatButton").Click += OnRepeatButtonClick;
+            this.Get<RepeatButton>("RepeatButton").Click += OnRepeatButtonClick;
         }
 
         private void InitializeComponent()
@@ -22,7 +22,7 @@ namespace ControlCatalog.Pages
         public void OnRepeatButtonClick(object sender, object args)
         {
             repeatButtonClickCount++;
-            var textBlock = this.FindControl<TextBlock>("RepeatButtonTextBlock");
+            var textBlock = this.Get<TextBlock>("RepeatButtonTextBlock");
             textBlock.Text = $"Repeat Button: {repeatButtonClickCount}";
         }
     }

samples/ControlCatalog/Pages/CalendarDatePickerPage.xaml.cs

@@ -10,11 +10,11 @@ namespace ControlCatalog.Pages
         {
             InitializeComponent();
             
-            var dp1 = this.FindControl<CalendarDatePicker>("DatePicker1");
-            var dp2 = this.FindControl<CalendarDatePicker>("DatePicker2");
-            var dp3 = this.FindControl<CalendarDatePicker>("DatePicker3");
-            var dp4 = this.FindControl<CalendarDatePicker>("DatePicker4");
-            var dp5 = this.FindControl<CalendarDatePicker>("DatePicker5");
+            var dp1 = this.Get<CalendarDatePicker>("DatePicker1");
+            var dp2 = this.Get<CalendarDatePicker>("DatePicker2");
+            var dp3 = this.Get<CalendarDatePicker>("DatePicker3");
+            var dp4 = this.Get<CalendarDatePicker>("DatePicker4");
+            var dp5 = this.Get<CalendarDatePicker>("DatePicker5");
 
             dp1.SelectedDate = DateTime.Today;
             dp2.SelectedDate = DateTime.Today.AddDays(10);
@@ -23,7 +23,7 @@ namespace ControlCatalog.Pages
 
             dp4.TemplateApplied += (s, e) =>
             {
-                dp4.BlackoutDates.AddDatesInPast();
+                dp4.BlackoutDates?.AddDatesInPast();
             };
             
         }

samples/ControlCatalog/Pages/CalendarPage.xaml.cs

@@ -11,11 +11,11 @@ namespace ControlCatalog.Pages
             this.InitializeComponent();
 
             var today = DateTime.Today; 
-            var cal1 = this.FindControl<Calendar>("DisplayDatesCalendar");
+            var cal1 = this.Get<Calendar>("DisplayDatesCalendar");
             cal1.DisplayDateStart = today.AddDays(-25);
             cal1.DisplayDateEnd = today.AddDays(25);
 
-            var cal2 = this.FindControl<Calendar>("BlackoutDatesCalendar");
+            var cal2 = this.Get<Calendar>("BlackoutDatesCalendar");
             cal2.BlackoutDates.AddDatesInPast();
             cal2.BlackoutDates.Add(new CalendarDateRange(today.AddDays(6)));
         }

samples/ControlCatalog/Pages/CarouselPage.xaml.cs

@@ -16,6 +16,11 @@ namespace ControlCatalog.Pages
         public CarouselPage()
         {
             this.InitializeComponent();
+            _carousel = this.Get<Carousel>("carousel");
+            _left = this.Get<Button>("left");
+            _right = this.Get<Button>("right");
+            _transition = this.Get<ComboBox>("transition");
+            _orientation = this.Get<ComboBox>("orientation");
             _left.Click += (s, e) => _carousel.Previous();
             _right.Click += (s, e) => _carousel.Next();
             _transition.SelectionChanged += TransitionChanged;
@@ -25,11 +30,7 @@ namespace ControlCatalog.Pages
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);
-            _carousel = this.FindControl<Carousel>("carousel");
-            _left = this.FindControl<Button>("left");
-            _right = this.FindControl<Button>("right");
-            _transition = this.FindControl<ComboBox>("transition");
-            _orientation = this.FindControl<ComboBox>("orientation");
+
         }
 
         private void TransitionChanged(object sender, SelectionChangedEventArgs e)

samples/ControlCatalog/Pages/ContextFlyoutPage.xaml.cs

@@ -18,29 +18,29 @@ namespace ControlCatalog.Pages
 
             DataContext = new ContextPageViewModel();
 
-            _textBox = this.FindControl<TextBox>("TextBox");
+            _textBox = this.Get<TextBox>("TextBox");
 
-            var cutButton = this.FindControl<Button>("CutButton");
+            var cutButton = this.Get<Button>("CutButton");
             cutButton.Click += CloseFlyout;
 
-            var copyButton = this.FindControl<Button>("CopyButton");
+            var copyButton = this.Get<Button>("CopyButton");
             copyButton.Click += CloseFlyout;
 
-            var pasteButton = this.FindControl<Button>("PasteButton");
+            var pasteButton = this.Get<Button>("PasteButton");
             pasteButton.Click += CloseFlyout;
 
-            var clearButton = this.FindControl<Button>("ClearButton");
+            var clearButton = this.Get<Button>("ClearButton");
             clearButton.Click += CloseFlyout;
 
-            var customContextRequestedBorder = this.FindControl<Border>("CustomContextRequestedBorder");
+            var customContextRequestedBorder = this.Get<Border>("CustomContextRequestedBorder");
             customContextRequestedBorder.AddHandler(ContextRequestedEvent, CustomContextRequested, RoutingStrategies.Tunnel);
 
-            var cancellableContextBorder = this.FindControl<Border>("CancellableContextBorder");
+            var cancellableContextBorder = this.Get<Border>("CancellableContextBorder");
             cancellableContextBorder.ContextFlyout!.Closing += ContextFlyoutPage_Closing;
             cancellableContextBorder.ContextFlyout!.Opening += ContextFlyoutPage_Opening;
         }
 
-        private ContextPageViewModel _model;
+        private ContextPageViewModel? _model;
         protected override void OnDataContextChanged(EventArgs e)
         {
             if (_model != null)
@@ -55,7 +55,7 @@ namespace ControlCatalog.Pages
         private void ContextFlyoutPage_Closing(object sender, CancelEventArgs e)
         {
             var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelCloseCheckBox");
-            e.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+            e.Cancel = cancelCloseCheckBox?.IsChecked ?? false;
         }
 
         private void ContextFlyoutPage_Opening(object sender, EventArgs e)
@@ -63,13 +63,13 @@ namespace ControlCatalog.Pages
             if (e is CancelEventArgs cancelArgs)
             {
                 var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelOpenCheckBox");
-                cancelArgs.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+                cancelArgs.Cancel = cancelCloseCheckBox?.IsChecked ?? false;
             }
         }
 
         private void CloseFlyout(object sender, RoutedEventArgs e)
         {
-            _textBox.ContextFlyout.Hide();
+            _textBox.ContextFlyout?.Hide();
         }
 
         public void CustomContextRequested(object sender, ContextRequestedEventArgs e)

samples/ControlCatalog/Pages/ContextMenuPage.xaml.cs

@@ -15,15 +15,15 @@ namespace ControlCatalog.Pages
             this.InitializeComponent();
             DataContext = new ContextPageViewModel();
 
-            var customContextRequestedBorder = this.FindControl<Border>("CustomContextRequestedBorder");
+            var customContextRequestedBorder = this.Get<Border>("CustomContextRequestedBorder");
             customContextRequestedBorder.AddHandler(ContextRequestedEvent, CustomContextRequested, RoutingStrategies.Tunnel);
 
-            var cancellableContextBorder = this.FindControl<Border>("CancellableContextBorder");
+            var cancellableContextBorder = this.Get<Border>("CancellableContextBorder");
             cancellableContextBorder.ContextMenu!.ContextMenuClosing += ContextFlyoutPage_Closing;
             cancellableContextBorder.ContextMenu!.ContextMenuOpening += ContextFlyoutPage_Opening;
         }
 
-        private ContextPageViewModel _model;
+        private ContextPageViewModel? _model;
         protected override void OnDataContextChanged(EventArgs e)
         {
             if (_model != null)

samples/ControlCatalog/Pages/DataGridPage.xaml.cs

@@ -21,7 +21,7 @@ namespace ControlCatalog.Pages
             var dataGridSortDescription = DataGridSortDescription.FromPath(nameof(Country.Region), ListSortDirection.Ascending, new ReversedStringComparer());
             var collectionView1 = new DataGridCollectionView(Countries.All);
             collectionView1.SortDescriptions.Add(dataGridSortDescription);
-            var dg1 = this.FindControl<DataGrid>("dataGrid1");
+            var dg1 = this.Get<DataGrid>("dataGrid1");
             dg1.IsReadOnly = true;
             dg1.LoadingRow += Dg1_LoadingRow;
             dg1.Sorting += (s, a) =>
@@ -37,7 +37,7 @@ namespace ControlCatalog.Pages
             };
             dg1.Items = collectionView1;
 
-            var dg2 = this.FindControl<DataGrid>("dataGridGrouping");
+            var dg2 = this.Get<DataGrid>("dataGridGrouping");
             dg2.IsReadOnly = true;
 
             var collectionView2 = new DataGridCollectionView(Countries.All);
@@ -45,7 +45,7 @@ namespace ControlCatalog.Pages
 
             dg2.Items = collectionView2;
 
-            var dg3 = this.FindControl<DataGrid>("dataGridEdit");
+            var dg3 = this.Get<DataGrid>("dataGridEdit");
             dg3.IsReadOnly = false;
 
             var items = new List<Person>
@@ -58,7 +58,7 @@ namespace ControlCatalog.Pages
 
             dg3.Items = collectionView3;
 
-            var addButton = this.FindControl<Button>("btnAdd");
+            var addButton = this.Get<Button>("btnAdd");
             addButton.Click += (a, b) => collectionView3.AddNew();
         }
 

samples/ControlCatalog/Pages/DateTimePickerPage.xaml.cs

@@ -9,12 +9,12 @@ namespace ControlCatalog.Pages
         public DateTimePickerPage()
         {
             this.InitializeComponent();
-            this.FindControl<TextBlock>("DatePickerDesc").Text = "Use a DatePicker to let users set a date in your app, " +
+            this.Get<TextBlock>("DatePickerDesc").Text = "Use a DatePicker to let users set a date in your app, " +
                 "for example to schedule an appointment. The DatePicker displays three controls for month, day, and year. " +
                 "These controls are easy to use with touch or mouse, and they can be styled and configured in several different ways. " +
                 "Order of month, day, and year is dynamically set based on user date settings";
 
-            this.FindControl<TextBlock>("TimePickerDesc").Text = "Use a TimePicker to let users set a time in your app, for example " +
+            this.Get<TextBlock>("TimePickerDesc").Text = "Use a TimePicker to let users set a time in your app, for example " +
                 "to set a reminder. The TimePicker displays three controls for hour, minute, and AM / PM(if necessary).These controls " +
                 "are easy to use with touch or mouse, and they can be styled and configured in several different ways. " +
                 "12 - hour or 24 - hour clock and visiblility of AM / PM is dynamically set based on user time settings, or can be overridden.";

samples/ControlCatalog/Pages/DialogsPage.xaml.cs

@@ -16,14 +16,14 @@ namespace ControlCatalog.Pages
         {
             this.InitializeComponent();
 
-            var results = this.FindControl<ItemsPresenter>("PickerLastResults");
-            var resultsVisible = this.FindControl<TextBlock>("PickerLastResultsVisible");
+            var results = this.Get<ItemsPresenter>("PickerLastResults");
+            var resultsVisible = this.Get<TextBlock>("PickerLastResultsVisible");
 
-            string lastSelectedDirectory = null;
+            string? lastSelectedDirectory = null;
 
             List<FileDialogFilter>? GetFilters()
             {
-                if (this.FindControl<CheckBox>("UseFilters").IsChecked != true)
+                if (this.Get<CheckBox>("UseFilters").IsChecked != true)
                     return null;
                 return  new List<FileDialogFilter>
                 {
@@ -39,7 +39,7 @@ namespace ControlCatalog.Pages
                 };
             }
 
-            this.FindControl<Button>("OpenFile").Click += async delegate
+            this.Get<Button>("OpenFile").Click += async delegate
             {
                 // Almost guaranteed to exist
                 var fullPath = Assembly.GetEntryAssembly()?.GetModules().FirstOrDefault()?.FullyQualifiedName;
@@ -56,7 +56,7 @@ namespace ControlCatalog.Pages
                 results.Items = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
-            this.FindControl<Button>("OpenMultipleFiles").Click += async delegate
+            this.Get<Button>("OpenMultipleFiles").Click += async delegate
             {
                 var result = await new OpenFileDialog()
                 {
@@ -68,7 +68,7 @@ namespace ControlCatalog.Pages
                 results.Items = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
-            this.FindControl<Button>("SaveFile").Click += async delegate
+            this.Get<Button>("SaveFile").Click += async delegate
             {
                 var result = await new SaveFileDialog()
                 {
@@ -80,7 +80,7 @@ namespace ControlCatalog.Pages
                 results.Items = new[] { result };
                 resultsVisible.IsVisible = result != null;
             };
-            this.FindControl<Button>("SelectFolder").Click += async delegate
+            this.Get<Button>("SelectFolder").Click += async delegate
             {
                 var result = await new OpenFolderDialog()
                 {
@@ -96,7 +96,7 @@ namespace ControlCatalog.Pages
                 results.Items = new [] { result };
                 resultsVisible.IsVisible = result != null;
             };
-            this.FindControl<Button>("OpenBoth").Click += async delegate
+            this.Get<Button>("OpenBoth").Click += async delegate
             {
                 var result = await new OpenFileDialog()
                 {
@@ -110,35 +110,35 @@ namespace ControlCatalog.Pages
                 results.Items = result;
                 resultsVisible.IsVisible = result?.Any() == true;
             };
-            this.FindControl<Button>("DecoratedWindow").Click += delegate
+            this.Get<Button>("DecoratedWindow").Click += delegate
             {
                 new DecoratedWindow().Show();
             };
-            this.FindControl<Button>("DecoratedWindowDialog").Click += delegate
+            this.Get<Button>("DecoratedWindowDialog").Click += delegate
             {
                 new DecoratedWindow().ShowDialog(GetWindow());
             };
-            this.FindControl<Button>("Dialog").Click += delegate
+            this.Get<Button>("Dialog").Click += delegate
             {
                 var window = CreateSampleWindow();
                 window.Height = 200;
                 window.ShowDialog(GetWindow());
             };
-            this.FindControl<Button>("DialogNoTaskbar").Click += delegate
+            this.Get<Button>("DialogNoTaskbar").Click += delegate
             {
                 var window = CreateSampleWindow();
                 window.Height = 200;
                 window.ShowInTaskbar = false;
                 window.ShowDialog(GetWindow());
             };
-            this.FindControl<Button>("OwnedWindow").Click += delegate
+            this.Get<Button>("OwnedWindow").Click += delegate
             {
                 var window = CreateSampleWindow();
 
                 window.Show(GetWindow());
             };
 
-            this.FindControl<Button>("OwnedWindowNoTaskbar").Click += delegate
+            this.Get<Button>("OwnedWindowNoTaskbar").Click += delegate
             {
                 var window = CreateSampleWindow();
 
@@ -191,7 +191,7 @@ namespace ControlCatalog.Pages
             return window;
         }
 
-        Window GetWindow() => (Window)this.VisualRoot;
+        Window GetWindow() => this.VisualRoot as Window  ?? throw new NullReferenceException("Invalid Owner");
 
         private void InitializeComponent()
         {

samples/ControlCatalog/Pages/DragAndDropPage.xaml.cs

@@ -14,7 +14,7 @@ namespace ControlCatalog.Pages
         public DragAndDropPage()
         {
             this.InitializeComponent();
-            _DropState = this.Find<TextBlock>("DropState");
+            _DropState = this.Get<TextBlock>("DropState");
 
             int textCount = 0;
             SetupDnd("Text", d => d.Set(DataFormats.Text,
@@ -26,8 +26,8 @@ namespace ControlCatalog.Pages
 
         void SetupDnd(string suffix, Action<DataObject> factory, DragDropEffects effects)
         {
-            var dragMe = this.Find<Border>("DragMe" + suffix);
-            var dragState = this.Find<TextBlock>("DragState"+suffix);
+            var dragMe = this.Get<Border>("DragMe" + suffix);
+            var dragState = this.Get<TextBlock>("DragState"+suffix);
 
             async void DoDrag(object sender, Avalonia.Input.PointerPressedEventArgs e)
             {

samples/ControlCatalog/Pages/FlyoutsPage.axaml.cs

@@ -35,7 +35,7 @@ namespace ControlCatalog.Pages
 
         private void SetXamlTexts()
         {
-            var bfxt = this.FindControl<TextBlock>("ButtonFlyoutXamlText");
+            var bfxt = this.Get<TextBlock>("ButtonFlyoutXamlText");
             bfxt.Text = "<Button Content=\"Click me!\">\n" +
                         "    <Button.Flyout>\n" +
                         "        <Flyout>\n" +
@@ -45,7 +45,7 @@ namespace ControlCatalog.Pages
                         "        </Flyout>\n" +
                         "    </Button.Flyout>\n</Button>";
 
-            var mfxt = this.FindControl<TextBlock>("MenuFlyoutXamlText");
+            var mfxt = this.Get<TextBlock>("MenuFlyoutXamlText");
             mfxt.Text = "<Button Content=\"Click me!\">\n" +
                     "    <Button.Flyout>\n" +
                     "        <MenuFlyout>\n" +
@@ -54,7 +54,7 @@ namespace ControlCatalog.Pages
                     "        </MenuFlyout>\n" +
                     "    </Button.Flyout>\n</Button>";
 
-            var afxt = this.FindControl<TextBlock>("AttachedFlyoutXamlText");
+            var afxt = this.Get<TextBlock>("AttachedFlyoutXamlText");
             afxt.Text = "<Panel Name=\"AttachedFlyoutPanel\">\n" +
                 "    <FlyoutBase.AttachedFlyout>\n" +
                 "        <Flyout>\n" +
@@ -66,7 +66,7 @@ namespace ControlCatalog.Pages
                 "\n\n In DoubleTapped handler:\n" +
                 "FlyoutBase.ShowAttachedFlyout(AttachedFlyoutPanel);";
 
-            var sfxt = this.FindControl<TextBlock>("SharedFlyoutXamlText");
+            var sfxt = this.Get<TextBlock>("SharedFlyoutXamlText");
             sfxt.Text = "Declare a flyout in Resources:\n" +
                 "<Window.Resources>\n" +
                 "    <Flyout x:Key=\"SharedFlyout\">\n" +

samples/ControlCatalog/Pages/ImagePage.xaml.cs

@@ -17,9 +17,9 @@ namespace ControlCatalog.Pages
         public ImagePage()
         {
             InitializeComponent();
-            _bitmapImage = this.FindControl<Image>("bitmapImage");
-            _drawingImage = this.FindControl<Image>("drawingImage");
-            _croppedImage = this.FindControl<Image>("croppedImage");
+            _bitmapImage = this.Get<Image>("bitmapImage");
+            _drawingImage = this.Get<Image>("drawingImage");
+            _croppedImage = this.Get<Image>("croppedImage");
         }
 
         private void InitializeComponent()
@@ -50,8 +50,11 @@ namespace ControlCatalog.Pages
             if (_croppedImage != null)
             {
                 var comboxBox = (ComboBox)sender;
-                var croppedBitmap = _croppedImage.Source as CroppedBitmap;
-                croppedBitmap.SourceRect = GetCropRect(comboxBox.SelectedIndex);
+                if (_croppedImage.Source is CroppedBitmap croppedBitmap)
+                {
+                    croppedBitmap.SourceRect = GetCropRect(comboxBox.SelectedIndex);
+                }
+                
             }
         }
 

samples/ControlCatalog/Pages/ItemsRepeaterPage.xaml.cs

@@ -24,11 +24,11 @@ namespace ControlCatalog.Pages
         public ItemsRepeaterPage()
         {
             this.InitializeComponent();
-            _repeater = this.FindControl<ItemsRepeater>("repeater");
-            _scroller = this.FindControl<ScrollViewer>("scroller");
-            _scrollToLast = this.FindControl<Button>("scrollToLast");
-            _scrollToRandom = this.FindControl<Button>("scrollToRandom");
-            _scrollToSelected = this.FindControl<Button>("scrollToSelected");
+            _repeater = this.Get<ItemsRepeater>("repeater");
+            _scroller = this.Get<ScrollViewer>("scroller");
+            _scrollToLast = this.Get<Button>("scrollToLast");
+            _scrollToRandom = this.Get<Button>("scrollToRandom");
+            _scrollToSelected = this.Get<Button>("scrollToSelected");
             _repeater.PointerPressed += RepeaterClick;
             _repeater.KeyDown += RepeaterOnKeyDown;
             _scrollToLast.Click += scrollToLast_Click;
@@ -44,8 +44,10 @@ namespace ControlCatalog.Pages
 
         public void OnSelectTemplateKey(object sender, SelectTemplateEventArgs e)
         {
-            var item = (ItemsRepeaterPageViewModel.Item)e.DataContext;
-            e.TemplateKey = (item.Index % 2 == 0) ? "even" : "odd";
+            if (e.DataContext is ItemsRepeaterPageViewModel.Item item)
+            {
+                e.TemplateKey = (item.Index % 2 == 0) ? "even" : "odd";
+            }
         }
 
         private void LayoutChanged(object sender, SelectionChangedEventArgs e)
@@ -115,7 +117,7 @@ namespace ControlCatalog.Pages
         private void ScrollTo(int index)
         {
             System.Diagnostics.Debug.WriteLine("Scroll to " + index);
-            var layoutManager = ((TopLevel)VisualRoot).LayoutManager;
+            var layoutManager = ((TopLevel)VisualRoot!).LayoutManager;
             var element = _repeater.GetOrCreateElement(index);
             layoutManager.ExecuteLayoutPass();
             element.BringIntoView();
@@ -123,9 +125,11 @@ namespace ControlCatalog.Pages
 
         private void RepeaterClick(object sender, PointerPressedEventArgs e)
         {
-            var item = (e.Source as TextBlock)?.DataContext as ItemsRepeaterPageViewModel.Item;
-            _viewModel.SelectedItem = item;
-            _selectedIndex = _viewModel.Items.IndexOf(item);
+            if ((e.Source as TextBlock)?.DataContext is ItemsRepeaterPageViewModel.Item item)
+            {
+                _viewModel.SelectedItem = item;
+                _selectedIndex = _viewModel.Items.IndexOf(item);
+            }
         }
 
         private void RepeaterOnKeyDown(object sender, KeyEventArgs e)

samples/ControlCatalog/Pages/LabelsPage.axaml.cs

@@ -7,7 +7,7 @@ namespace ControlCatalog.Pages
 {
     public class LabelsPage : UserControl
     {
-        private Person _person;
+        private Person? _person;
 
         public LabelsPage()
         {

samples/ControlCatalog/Pages/MenuPage.xaml.cs

@@ -22,7 +22,7 @@ namespace ControlCatalog.Pages
             AvaloniaXamlLoader.Load(this);
         }
         
-        private MenuPageViewModel _model;
+        private MenuPageViewModel? _model;
         protected override void OnDataContextChanged(EventArgs e)
         {
             if (_model != null)

samples/ControlCatalog/Pages/NativeEmbedPage.xaml.cs

@@ -79,6 +79,8 @@ namespace ControlCatalog.Pages
     public interface INativeDemoControl
     {
         /// <param name="isSecond">Used to specify which control should be displayed as a demo</param>
+        /// <param name="parent"></param>
+        /// <param name="createDefault"></param>
         IPlatformHandle CreateControl(bool isSecond, IPlatformHandle parent, Func<IPlatformHandle> createDefault);
     }
 }

samples/ControlCatalog/Pages/NumericUpDownPage.xaml

@@ -65,7 +65,7 @@
                        Margin="2" HorizontalAlignment="Center"/>
 
         <TextBlock Grid.Row="3" Grid.Column="0" VerticalAlignment="Center" Margin="10,2,2,2">Value:</TextBlock>
-        <NumericUpDown Grid.Row="3" Grid.Column="1" Value="{Binding #upDown.Value}" VerticalAlignment="Center"
+        <NumericUpDown Grid.Row="3" Grid.Column="1" Value="{Binding DecimalValue}" VerticalAlignment="Center"
                        Margin="2" HorizontalAlignment="Center"/>
 
 

samples/ControlCatalog/Pages/NumericUpDownPage.xaml.cs

@@ -28,16 +28,16 @@ namespace ControlCatalog.Pages
 
     public class NumbersPageViewModel : ViewModelBase
     {
-        private IList<FormatObject> _formats;
+        private IList<FormatObject>? _formats;
         private FormatObject _selectedFormat;
-        private IList<Location> _spinnerLocations;
+        private IList<Location>? _spinnerLocations;
 
         private double _doubleValue;
         private decimal _decimalValue;
 
         public NumbersPageViewModel()
         {
-            SelectedFormat = Formats.FirstOrDefault();
+            _selectedFormat = Formats.FirstOrDefault();
         }
 
         public double DoubleValue
@@ -103,7 +103,7 @@ namespace ControlCatalog.Pages
 
     public class FormatObject
     {
-        public string Value { get; set; }
-        public string Name { get; set; }
+        public string? Value { get; set; }
+        public string? Name { get; set; }
     }
 }

samples/ControlCatalog/Pages/ScreenPage.cs

@@ -18,7 +18,7 @@ namespace ControlCatalog.Pages
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTree(e);
-            Window w = (Window)VisualRoot;
+            Window w = (Window)VisualRoot!;
             w.PositionChanged += (sender, args) => InvalidateVisual();
         }
 

samples/ControlCatalog/Pages/TabControlPage.xaml.cs

@@ -52,7 +52,7 @@ namespace ControlCatalog.Pages
 
         private IBitmap LoadBitmap(string uri)
         {
-            var assets = AvaloniaLocator.Current.GetService<IAssetLoader>();
+            var assets = AvaloniaLocator.Current!.GetService<IAssetLoader>()!;
             return new Bitmap(assets.Open(new Uri(uri)));
         }
 
@@ -60,7 +60,7 @@ namespace ControlCatalog.Pages
         {
             private Dock _tabPlacement;
 
-            public TabItemViewModel[] Tabs { get; set; }
+            public TabItemViewModel[]? Tabs { get; set; }
 
             public Dock TabPlacement
             {
@@ -71,10 +71,10 @@ namespace ControlCatalog.Pages
 
         private class TabItemViewModel
         {
-            public string Header { get; set; }
-            public string Text { get; set; }
-            public IBitmap Image { get; set; }
-            public bool IsEnabled { get; set; } = true;           
+            public string? Header { get; set; }
+            public string? Text { get; set; }
+            public IBitmap? Image { get; set; }
+            public bool IsEnabled { get; set; } = true;
         }
     }
 }

samples/ControlCatalog/Pages/TabStripPage.xaml.cs

@@ -38,7 +38,7 @@ namespace ControlCatalog.Pages
 
         private class TabStripItemViewModel
         {
-            public string Header { get; set; }
+            public string? Header { get; set; }
             public bool IsEnabled { get; set; } = true;
         }
     }

samples/ControlCatalog/ViewModels/ApplicationViewModel.cs

@@ -10,7 +10,7 @@ namespace ControlCatalog.ViewModels
         {
             ExitCommand = MiniCommand.Create(() =>
             {
-                if (Application.Current.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime lifetime)
+                if (Application.Current?.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime lifetime)
                 {
                     lifetime.Shutdown();
                 }

samples/ControlCatalog/ViewModels/ContextPageViewModel.cs

@@ -9,7 +9,7 @@ namespace ControlCatalog.ViewModels
 {
     public class ContextPageViewModel
     {
-        public Control View { get; set; }
+        public Control? View { get; set; }
         public ContextPageViewModel()
         {
             OpenCommand = MiniCommand.CreateFromTask(Open);

samples/ControlCatalog/ViewModels/CursorPageViewModel.cs

@@ -18,7 +18,7 @@ namespace ControlCatalog.ViewModels
                 .Select(x => new StandardCursorModel(x))
                 .ToList();
 
-            var loader = AvaloniaLocator.Current.GetService<IAssetLoader>();
+            var loader = AvaloniaLocator.Current!.GetService<IAssetLoader>()!;
             var s = loader.Open(new Uri("avares://ControlCatalog/Assets/avalonia-32.png"));
             var bitmap = new Bitmap(s);
             CustomCursor = new Cursor(bitmap, new PixelPoint(16, 16));

samples/ControlCatalog/ViewModels/ItemsRepeaterPageViewModel.cs

@@ -14,7 +14,7 @@ namespace ControlCatalog.ViewModels
 
         public ItemsRepeaterPageViewModel()
         {
-            Items = CreateItems();
+            _items = CreateItems();
         }
 
         public ObservableCollection<Item> Items
@@ -23,12 +23,12 @@ namespace ControlCatalog.ViewModels
             set => this.RaiseAndSetIfChanged(ref _items, value);
         }
 
-        public Item SelectedItem { get; set; }
+        public Item? SelectedItem { get; set; }
 
         public void AddItem()
         {
             var index = SelectedItem != null ? Items.IndexOf(SelectedItem) : -1;
-            Items.Insert(index + 1, new Item(index + 1) { Text = $"New Item {_newItemIndex++}" });
+            Items.Insert(index + 1, new Item(index + 1, $"New Item {_newItemIndex++}"));
         }
 
         public void RemoveItem()
@@ -66,19 +66,20 @@ namespace ControlCatalog.ViewModels
             _newGenerationIndex++;
 
             return new ObservableCollection<Item>(
-                Enumerable.Range(1, 100000).Select(i => new Item(i)
-                {
-                    Text = $"Item {i.ToString()} {suffix}"
-                }));
+                Enumerable.Range(1, 100000).Select(i => new Item(i, $"Item {i.ToString()} {suffix}")));
         }
 
         public class Item : ViewModelBase
         {
             private double _height = double.NaN;
 
-            public Item(int index) => Index = index;
+            public Item(int index, string text)
+            {
+                Index = index;
+                Text = text;
+            }
             public int Index { get; }
-            public string Text { get; set; }
+            public string Text { get; }
             
             public double Height 
             {

samples/ControlCatalog/ViewModels/MainWindowViewModel.cs

@@ -16,11 +16,11 @@ namespace ControlCatalog.ViewModels
 
         private bool _isMenuItemChecked = true;
         private WindowState _windowState;
-        private WindowState[] _windowStates;
+        private WindowState[] _windowStates = Array.Empty<WindowState>();
         private int _transparencyLevel;
         private ExtendClientAreaChromeHints _chromeHints = ExtendClientAreaChromeHints.PreferSystemChrome;
         private bool _extendClientAreaEnabled;
-        private bool _systemTitleBarEnabled;        
+        private bool _systemTitleBarEnabled;
         private bool _preferSystemChromeEnabled;
         private double _titleBarHeight;
 
@@ -47,14 +47,15 @@ namespace ControlCatalog.ViewModels
             {
                 var dialog = new AboutAvaloniaDialog();
 
-                var mainWindow = (App.Current.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow;
-
-                await dialog.ShowDialog(mainWindow);
+                if ((App.Current?.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow is { } mainWindow)
+                {
+                    await dialog.ShowDialog(mainWindow);
+                }
             });
 
             ExitCommand = MiniCommand.Create(() =>
             {
-                (App.Current.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime).Shutdown();
+                (App.Current?.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.Shutdown();
             });
 
             ToggleMenuItemCheckedCommand = MiniCommand.Create(() =>

samples/ControlCatalog/ViewModels/MenuItemViewModel.cs

@@ -5,9 +5,9 @@ namespace ControlCatalog.ViewModels
 {
     public class MenuItemViewModel
     {
-        public string Header { get; set; }
-        public ICommand Command { get; set; }
-        public object CommandParameter { get; set; }
-        public IList<MenuItemViewModel> Items { get; set; }
+        public string? Header { get; set; }
+        public ICommand? Command { get; set; }
+        public object? CommandParameter { get; set; }
+        public IList<MenuItemViewModel>? Items { get; set; }
     }
 }

samples/ControlCatalog/ViewModels/MenuPageViewModel.cs

@@ -10,7 +10,7 @@ namespace ControlCatalog.ViewModels
 {
     public class MenuPageViewModel
     {
-        public Control View { get; set; }
+        public Control? View { get; set; }
         public MenuPageViewModel()
         {
             OpenCommand = MiniCommand.CreateFromTask(Open);

samples/ControlCatalog/ViewModels/NotificationViewModel.cs

@@ -19,8 +19,8 @@ namespace ControlCatalog.ViewModels
             });
         }
 
-        public string Title { get; set; }
-        public string Message { get; set; }
+        public string? Title { get; set; }
+        public string? Message { get; set; }
 
         public MiniCommand YesCommand { get; }
 

samples/ControlCatalog/ViewModels/TransitioningContentControlPageViewModel.cs

@@ -19,7 +19,7 @@ namespace ControlCatalog.ViewModels
     {
         public TransitioningContentControlPageViewModel()
         {
-            var assetLoader = AvaloniaLocator.Current.GetService<IAssetLoader>();
+            var assetLoader = AvaloniaLocator.Current?.GetService<IAssetLoader>()!;
 
             var images = new string[] 
             { 
@@ -36,8 +36,8 @@ namespace ControlCatalog.ViewModels
 
             SetupTransitions();
 
-            SelectedTransition = PageTransitions[1];
-            SelectedImage = Images[0];
+            _SelectedTransition = PageTransitions[1];
+            _SelectedImage = Images[0];
         }
 
         public List<PageTransition> PageTransitions { get; } = new List<PageTransition>();
@@ -45,12 +45,12 @@ namespace ControlCatalog.ViewModels
         public List<Bitmap> Images { get; } = new List<Bitmap>();
 
 
-        private Bitmap? _SelectedImage;
+        private Bitmap _SelectedImage;
 
         /// <summary>
         /// Gets or Sets the selected image
         /// </summary>
-        public Bitmap? SelectedImage
+        public Bitmap SelectedImage
         {
             get { return _SelectedImage; }
             set { this.RaiseAndSetIfChanged(ref _SelectedImage, value); }
@@ -160,12 +160,12 @@ namespace ControlCatalog.ViewModels
         public string DisplayTitle { get; }
 
 
-        private IPageTransition _Transition;
+        private IPageTransition? _Transition;
 
         /// <summary>
         /// Gets or sets the transition
         /// </summary>
-        public IPageTransition Transition
+        public IPageTransition? Transition
         {
             get { return _Transition; }
             set { this.RaiseAndSetIfChanged(ref _Transition, value); }
@@ -201,7 +201,7 @@ namespace ControlCatalog.ViewModels
         /// </summary>
         public TimeSpan Duration { get; set; }
 
-        public async Task Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken)
+        public async Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken)
         {
             if (cancellationToken.IsCancellationRequested)
             {

samples/ControlCatalog/ViewModels/TreeViewPageViewModel.cs

@@ -92,7 +92,7 @@ namespace ControlCatalog.ViewModels
 
         public class Node
         {
-            private ObservableCollection<Node> _children;
+            private ObservableCollection<Node>? _children;
             private int _childIndex = 10;
 
             public Node()
@@ -106,7 +106,7 @@ namespace ControlCatalog.ViewModels
                 Header = parent.Header + ' ' + index;
             }
 
-            public Node Parent { get; }
+            public Node? Parent { get; }
             public string Header { get; }
             public bool AreChildrenInitialized => _children != null;
             public ObservableCollection<Node> Children => _children ??= CreateChildren();

src/Android/Avalonia.Android/AvaloniaView.cs

@@ -15,7 +15,7 @@ namespace Avalonia.Android
         private EmbeddableControlRoot _root;
         private readonly ViewImpl _view;
 
-        private IDisposable? _timerSubscription;
+        private IDisposable _timerSubscription;
 
         public AvaloniaView(Context context) : base(context)
         {

src/Android/Avalonia.Android/Platform/Specific/Helpers/AndroidKeyboardEventsHelper.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Android.Platform.Specific.Helpers
             return DispatchKeyEventInternal(e, out callBase);
         }
 
-        string? UnicodeTextInput(KeyEvent keyEvent)
+        string UnicodeTextInput(KeyEvent keyEvent)
         {
             return keyEvent.Action == KeyEventActions.Multiple
                 && keyEvent.RepeatCount == 0

src/Avalonia.Base/Matrix.cs

@@ -9,14 +9,14 @@ namespace Avalonia
     /// <summary>
     /// A 3x3 matrix.
     /// </summary>
-    /// <remakrs>Matrix layout:
+    /// <remarks>Matrix layout:
     ///         | 1st col | 2nd col | 3r col |
-    /// 1st row | scaleX  | skrewY  | persX  |
-    /// 2nd row | skrewX  | scaleY  | persY  |
-    /// 3rd row | transX  | transY  | persZ  |
+    /// 1st row | scaleX  | skewY  | perspX  |
+    /// 2nd row | skewX  | scaleY  | perspY  |
+    /// 3rd row | transX  | transY  | perspZ  |
     /// 
-    /// Note: Skia.SkMatrix uses a transposed layout (where for example skrewX/skrewY and perspp0/tranX are swapped).
-    /// </remakrs>
+    /// Note: Skia.SkMatrix uses a transposed layout (where for example skewX/skewY and persp0/transX are swapped).
+    /// </remarks>
 #if !BUILDTASK
     public
 #endif
@@ -36,18 +36,18 @@ namespace Avalonia
         /// Initializes a new instance of the <see cref="Matrix"/> struct (equivalent to a 2x3 Matrix without perspective).
         /// </summary>
         /// <param name="scaleX">The first element of the first row.</param>
-        /// <param name="skrewY">The second element of the first row.</param>
-        /// <param name="skrewX">The first element of the second row.</param>
+        /// <param name="skewY">The second element of the first row.</param>
+        /// <param name="skewX">The first element of the second row.</param>
         /// <param name="scaleY">The second element of the second row.</param>
         /// <param name="offsetX">The first element of the third row.</param>
         /// <param name="offsetY">The second element of the third row.</param>
         public Matrix(
             double scaleX,
-            double skrewY,
-            double skrewX,
+            double skewY,
+            double skewX,
             double scaleY,
             double offsetX,
-            double offsetY) : this( scaleX, skrewY, 0, skrewX, scaleY, 0, offsetX, offsetY, 1)
+            double offsetY) : this( scaleX, skewY, 0, skewX, scaleY, 0, offsetX, offsetY, 1)
         {
         }
 
@@ -57,34 +57,34 @@ namespace Avalonia
         /// Initializes a new instance of the <see cref="Matrix"/> struct.
         /// </summary>
         /// <param name="scaleX">The first element of the first row.</param>
-        /// <param name="skrewY">The second element of the first row.</param>
-        /// <param name="persX">The third element of the first row.</param>
-        /// <param name="skrewX">The first element of the second row.</param>
+        /// <param name="skewY">The second element of the first row.</param>
+        /// <param name="perspX">The third element of the first row.</param>
+        /// <param name="skewX">The first element of the second row.</param>
         /// <param name="scaleY">The second element of the second row.</param>
-        /// <param name="persY">The third element of the second row.</param>
+        /// <param name="perspY">The third element of the second row.</param>
         /// <param name="offsetX">The first element of the third row.</param>
         /// <param name="offsetY">The second element of the third row.</param>
-        /// <param name="persZ">The third element of the third row.</param>
+        /// <param name="perspZ">The third element of the third row.</param>
         public Matrix(
             double scaleX,
-            double skrewY,
-            double persX,
-            double skrewX,
+            double skewY,
+            double perspX,
+            double skewX,
             double scaleY,
-            double persY, 
+            double perspY, 
             double offsetX,
             double offsetY,
-            double persZ)
+            double perspZ)
         {
             _m11 = scaleX;
-            _m12 = skrewY;
-            _m13 = persX;
-            _m21 = skrewX;
+            _m12 = skewY;
+            _m13 = perspX;
+            _m21 = skewX;
             _m22 = scaleY;
-            _m23 = persY;
+            _m23 = perspY;
             _m31 = offsetX;
             _m32 = offsetY;
-            _m33 = persZ;
+            _m33 = perspZ;
         }
 
         /// <summary>
@@ -111,17 +111,17 @@ namespace Avalonia
         public double M11 => _m11;
 
         /// <summary>
-        /// The second element of the first row (skrewY).
+        /// The second element of the first row (skewY).
         /// </summary>
         public double M12 => _m12;
 
         /// <summary>
-        /// The third element of the first row (persX: input x-axis perspective factor).
+        /// The third element of the first row (perspX: input x-axis perspective factor).
         /// </summary>
         public double M13 => _m13;
 
         /// <summary>
-        /// The first element of the second row (skrewX).
+        /// The first element of the second row (skewX).
         /// </summary>
         public double M21 => _m21;
 
@@ -131,7 +131,7 @@ namespace Avalonia
         public double M22 => _m22;
 
         /// <summary>
-        /// The third element of the second row (persY: input y-axis perspective factor).
+        /// The third element of the second row (perspY: input y-axis perspective factor).
         /// </summary>
         public double M23 => _m23;
 
@@ -146,7 +146,7 @@ namespace Avalonia
         public double M32 => _m32;
 
         /// <summary>
-        /// The third element of the third row (persZ: perspective scale factor).
+        /// The third element of the third row (perspZ: perspective scale factor).
         /// </summary>
         public double M33 => _m33;
 
@@ -450,13 +450,13 @@ namespace Avalonia
             
             inverted = new Matrix(
                 (_m22 * _m33 - _m32 * _m23) * invdet,
-                (_m13 * _m31 - _m12 * _m33) * invdet,
+                (_m13 * _m32 - _m12 * _m33) * invdet,
                 (_m12 * _m23 - _m13 * _m22) * invdet,
                 (_m23 * _m31 - _m21 * _m33) * invdet,
                 (_m11 * _m33 - _m13 * _m31) * invdet,
                 (_m21 * _m13 - _m11 * _m23) * invdet,
                 (_m21 * _m32 - _m31 * _m22) * invdet,
-                (_m21 * _m12 - _m11 * _m32) * invdet,
+                (_m31 * _m12 - _m11 * _m32) * invdet,
                 (_m11 * _m22 - _m21 * _m12) * invdet
                 );
             
@@ -481,7 +481,7 @@ namespace Avalonia
         /// <summary>
         /// Parses a <see cref="Matrix"/> string.
         /// </summary>
-        /// <param name="s">Six or nine comma-delimited double values (m11, m12, m21, m22, offsetX, offsetY[, persX, persY, persZ]) that describe the new <see cref="Matrix"/></param>
+        /// <param name="s">Six or nine comma-delimited double values (m11, m12, m21, m22, offsetX, offsetY[, perspX, perspY, perspZ]) that describe the new <see cref="Matrix"/></param>
         /// <returns>The <see cref="Matrix"/>.</returns>
         public static Matrix Parse(string s)
         {
@@ -497,11 +497,11 @@ namespace Avalonia
                 var v4 = tokenizer.ReadDouble();
                 var v5 = tokenizer.ReadDouble();
                 var v6 = tokenizer.ReadDouble();
-                var pers = tokenizer.TryReadDouble(out var v7);
-                pers = pers && tokenizer.TryReadDouble(out v8);
-                pers = pers && tokenizer.TryReadDouble(out v9);
+                var persp = tokenizer.TryReadDouble(out var v7);
+                persp = persp && tokenizer.TryReadDouble(out v8);
+                persp = persp && tokenizer.TryReadDouble(out v9);
 
-                if (pers) 
+                if (persp) 
                     return new Matrix(v1, v2, v7, v3, v4, v8, v5, v6, v9);
                 else
                     return new Matrix(v1, v2, v3, v4, v5, v6);

src/Avalonia.Base/Media/GeometryDrawing.cs

@@ -68,7 +68,8 @@ namespace Avalonia.Media
 
         public override Rect GetBounds()
         {
-            return Geometry?.GetRenderBounds(s_boundsPen) ?? Rect.Empty;
+            IPen pen = Pen ?? s_boundsPen;
+			return Geometry?.GetRenderBounds(pen) ?? Rect.Empty;
         }
     }
 }

src/Avalonia.Base/Reactive/TypedBindingAdapter.cs

@@ -30,13 +30,15 @@ namespace Avalonia.Reactive
             }
             catch (InvalidCastException e)
             {
+                var unwrappedValue = value.HasValue ? value.Value : null;
+                
                 Logger.TryGet(LogEventLevel.Error, LogArea.Binding)?.Log(
                     _target,
                     "Binding produced invalid value for {$Property} ({$PropertyType}): {$Value} ({$ValueType})",
                     _property.Name,
                     _property.PropertyType,
-                    value.Value,
-                    value.Value?.GetType());
+                    unwrappedValue,
+                    unwrappedValue?.GetType());
                 PublishNext(BindingValue<T>.BindingError(e));
             }
         }

src/Avalonia.Controls/Avalonia.Controls.csproj

@@ -2,9 +2,6 @@
   <PropertyGroup>
     <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
-  <ItemGroup>
-    <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Base\Avalonia.Base.csproj" />
     <ProjectReference Include="..\Avalonia.Remote.Protocol\Avalonia.Remote.Protocol.csproj" />

src/Avalonia.Controls/Button.cs

@@ -232,6 +232,13 @@ namespace Avalonia.Controls
                     StopListeningForDefault(inputElement);
                 }
             }
+            if (IsCancel)
+            {
+                if (e.Root is IInputElement inputElement)
+                {
+                    StopListeningForCancel(inputElement);
+                }
+            }
         }
 
         /// <inheritdoc/>

src/Avalonia.Controls/Calendar/CalendarItem.cs

@@ -218,7 +218,7 @@ namespace Avalonia.Controls.Primitives
             if (YearView != null)
             {
                 var childCount = Calendar.RowsPerYear * Calendar.ColumnsPerYear;
-                var children = new List<IControl>(childCount);
+                using var children = new PooledList<IControl>(childCount);
 
                 EventHandler<PointerPressedEventArgs> monthCalendarButtonMouseDown = Month_CalendarButtonMouseDown;
                 EventHandler<PointerReleasedEventArgs> monthCalendarButtonMouseUp = Month_CalendarButtonMouseUp;

src/Avalonia.Controls/Carousel.cs

@@ -20,8 +20,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="PageTransition"/> property.
         /// </summary>
-        public static readonly StyledProperty<IPageTransition> PageTransitionProperty =
-            AvaloniaProperty.Register<Carousel, IPageTransition>(nameof(PageTransition));
+        public static readonly StyledProperty<IPageTransition?> PageTransitionProperty =
+            AvaloniaProperty.Register<Carousel, IPageTransition?>(nameof(PageTransition));
 
         /// <summary>
         /// The default value of <see cref="ItemsControl.ItemsPanelProperty"/> for 
@@ -54,7 +54,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the transition to use when moving between pages.
         /// </summary>
-        public IPageTransition PageTransition
+        public IPageTransition? PageTransition
         {
             get { return GetValue(PageTransitionProperty); }
             set { SetValue(PageTransitionProperty, value); }

src/Avalonia.Controls/NumericUpDown/NumericUpDown.cs

@@ -107,8 +107,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Value"/> property.
         /// </summary>
-        public static readonly DirectProperty<NumericUpDown, decimal> ValueProperty =
-            AvaloniaProperty.RegisterDirect<NumericUpDown, decimal>(nameof(Value), updown => updown.Value,
+        public static readonly DirectProperty<NumericUpDown, decimal?> ValueProperty =
+            AvaloniaProperty.RegisterDirect<NumericUpDown, decimal?>(nameof(Value), updown => updown.Value,
                 (updown, v) => updown.Value = v, defaultBindingMode: BindingMode.TwoWay, enableDataValidation: true);
 
         /// <summary>
@@ -131,7 +131,7 @@ namespace Avalonia.Controls
 
         private IDisposable? _textBoxTextChangedSubscription;
 
-        private decimal _value;
+        private decimal? _value;
         private string? _text;
         private bool _internalValueSet;
         private bool _clipValueToMinMax;
@@ -277,7 +277,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the value.
         /// </summary>
-        public decimal Value
+        public decimal? Value
         {
             get { return _value; }
             set
@@ -351,7 +351,7 @@ namespace Avalonia.Controls
         /// <inheritdoc />
         protected override void OnLostFocus(RoutedEventArgs e)
         {
-            CommitInput();
+            CommitInput(true);
             base.OnLostFocus(e);
         }
 
@@ -489,9 +489,9 @@ namespace Avalonia.Controls
             {
                 SetValidSpinDirection();
             }
-            if (ClipValueToMinMax)
+            if (ClipValueToMinMax && Value.HasValue)
             {
-                Value = MathUtilities.Clamp(Value, Minimum, Maximum);
+                Value = MathUtilities.Clamp(Value.Value, Minimum, Maximum);
             }
         }
 
@@ -506,9 +506,9 @@ namespace Avalonia.Controls
             {
                 SetValidSpinDirection();
             }
-            if (ClipValueToMinMax)
+            if (ClipValueToMinMax && Value.HasValue)
             {
-                Value = MathUtilities.Clamp(Value, Minimum, Maximum);
+                Value = MathUtilities.Clamp(Value.Value, Minimum, Maximum);
             }
         }
 
@@ -530,7 +530,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void OnValueChanged(decimal oldValue, decimal newValue)
+        protected virtual void OnValueChanged(decimal? oldValue, decimal? newValue)
         {
             if (!_internalValueSet && IsInitialized)
             {
@@ -573,7 +573,7 @@ namespace Avalonia.Controls
         /// Called when the <see cref="Value"/> property has to be coerced.
         /// </summary>
         /// <param name="baseValue">The value.</param>
-        protected virtual decimal OnCoerceValue(decimal baseValue)
+        protected virtual decimal? OnCoerceValue(decimal? baseValue)
         {
             return baseValue;
         }
@@ -607,7 +607,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void RaiseValueChangedEvent(decimal oldValue, decimal newValue)
+        protected virtual void RaiseValueChangedEvent(decimal? oldValue, decimal? newValue)
         {
             var e = new NumericUpDownValueChangedEventArgs(ValueChangedEvent, oldValue, newValue);
             RaiseEvent(e);
@@ -616,9 +616,9 @@ namespace Avalonia.Controls
         /// <summary>
         /// Converts the formatted text to a value.
         /// </summary>
-        private decimal ConvertTextToValue(string text)
+        private decimal? ConvertTextToValue(string? text)
         {
-            decimal result = 0;
+            decimal? result = null;
 
             if (string.IsNullOrEmpty(text))
             {
@@ -635,9 +635,9 @@ namespace Avalonia.Controls
 
             result = ConvertTextToValueCore(currentValueText, text);
 
-            if (ClipValueToMinMax)
+            if (ClipValueToMinMax && result.HasValue)
             {
-                return MathUtilities.Clamp(result, Minimum, Maximum);
+                return MathUtilities.Clamp(result.Value, Minimum, Maximum);
             }
 
             ValidateMinMax(result);
@@ -649,7 +649,7 @@ namespace Avalonia.Controls
         /// Converts the value to formatted text.
         /// </summary>
         /// <returns></returns>
-        private string ConvertValueToText()
+        private string? ConvertValueToText()
         {
             //Manage FormatString of type "{}{0:N2} °" (in xaml) or "{0:N2} °" in code-behind.
             if (FormatString.Contains("{0"))
@@ -657,7 +657,7 @@ namespace Avalonia.Controls
                 return string.Format(NumberFormat, FormatString, Value);
             }
 
-            return Value.ToString(FormatString, NumberFormat);
+            return Value?.ToString(FormatString, NumberFormat);
         }
 
         /// <summary>
@@ -665,7 +665,16 @@ namespace Avalonia.Controls
         /// </summary>
         private void OnIncrement()
         {
-            var result = Value + Increment;
+            decimal result;
+            if (Value.HasValue)
+            {
+                result = Value.Value + Increment;
+            }
+            else
+            {
+                result = Minimum;
+            }
+            
             Value = MathUtilities.Clamp(result, Minimum, Maximum);
         }
 
@@ -674,7 +683,17 @@ namespace Avalonia.Controls
         /// </summary>
         private void OnDecrement()
         {
-            var result = Value - Increment;
+            decimal result;
+            
+            if (Value.HasValue)
+            {
+                result = Value.Value - Increment;
+            }
+            else
+            {
+                result = Maximum;
+            }
+            
             Value = MathUtilities.Clamp(result, Minimum, Maximum);
         }
 
@@ -688,6 +707,11 @@ namespace Avalonia.Controls
             // Zero increment always prevents spin.
             if (Increment != 0 && !IsReadOnly)
             {
+                if (!Value.HasValue)
+                {
+                    validDirections = ValidSpinDirections.Increase | ValidSpinDirections.Decrease;
+                }
+                
                 if (Value < Maximum)
                 {
                     validDirections = validDirections | ValidSpinDirections.Increase;
@@ -825,13 +849,13 @@ namespace Avalonia.Controls
         {
             if (e.Sender is NumericUpDown upDown)
             {
-                var oldValue = (decimal)e.OldValue!;
-                var newValue = (decimal)e.NewValue!;
+                var oldValue = (decimal?)e.OldValue;
+                var newValue = (decimal?)e.NewValue;
                 upDown.OnValueChanged(oldValue, newValue);
             }
         }
 
-        private void SetValueInternal(decimal value)
+        private void SetValueInternal(decimal? value)
         {
             _internalValueSet = true;
             try
@@ -946,9 +970,9 @@ namespace Avalonia.Controls
             remove { RemoveHandler(ValueChangedEvent, value); }
         }
 
-        private bool CommitInput()
+        private bool CommitInput(bool forceTextUpdate = false)
         {
-            return SyncTextAndValueProperties(true, Text);
+            return SyncTextAndValueProperties(true, Text, forceTextUpdate);
         }
 
         /// <summary>
@@ -978,28 +1002,24 @@ namespace Avalonia.Controls
             {
                 if (updateValueFromText)
                 {
-                    if (!string.IsNullOrEmpty(text))
+                    try
                     {
-                        try
+                        var newValue = ConvertTextToValue(text);
+                        if (!Equals(newValue, Value))
                         {
-                            var newValue = ConvertTextToValue(text);
-                            if (!Equals(newValue, Value))
-                            {
-                                SetValueInternal(newValue);
-                            }
-                        }
-                        catch
-                        {
-                            parsedTextIsValid = false;
+                            SetValueInternal(newValue);
                         }
                     }
+                    catch
+                    {
+                        parsedTextIsValid = false;
+                    }
                 }
 
                 // Do not touch the ongoing text input from user.
                 if (!_isTextChangedFromUI)
                 {
-                    var keepEmpty = !forceTextUpdate && string.IsNullOrEmpty(Text);
-                    if (!keepEmpty)
+                    if (forceTextUpdate)
                     {
                         var newText = ConvertValueToText();
                         if (!Equals(Text, newText))
@@ -1036,10 +1056,15 @@ namespace Avalonia.Controls
             return parsedTextIsValid;
         }
 
-        private decimal ConvertTextToValueCore(string currentValueText, string text)
+        private decimal? ConvertTextToValueCore(string? currentValueText, string? text)
         {
             decimal result;
 
+            if (string.IsNullOrEmpty(text))
+            {
+                return null;
+            }
+            
             if (IsPercent(FormatString))
             {
                 result = ParsePercent(text, NumberFormat);
@@ -1052,7 +1077,7 @@ namespace Avalonia.Controls
                     var shouldThrow = true;
 
                     // Check if CurrentValueText is also failing => it also contains special characters. ex : 90°
-                    if (!decimal.TryParse(currentValueText, ParsingNumberStyle, NumberFormat, out var _))
+                    if (!string.IsNullOrEmpty(currentValueText) && !decimal.TryParse(currentValueText, ParsingNumberStyle, NumberFormat, out var _))
                     {
                         // extract non-digit characters
                         var currentValueTextSpecialCharacters = currentValueText.Where(c => !char.IsDigit(c));
@@ -1082,8 +1107,12 @@ namespace Avalonia.Controls
             return result;
         }
 
-        private void ValidateMinMax(decimal value)
+        private void ValidateMinMax(decimal? value)
         {
+            if (!value.HasValue)
+            {
+                return;
+            }
             if (value < Minimum)
             {
                 throw new ArgumentOutOfRangeException(nameof(value), string.Format("Value must be greater than Minimum value of {0}", Minimum));

src/Avalonia.Controls/NumericUpDown/NumericUpDownValueChangedEventArgs.cs

@@ -4,13 +4,13 @@ namespace Avalonia.Controls
 {
     public class NumericUpDownValueChangedEventArgs : RoutedEventArgs
     {
-        public NumericUpDownValueChangedEventArgs(RoutedEvent routedEvent, decimal oldValue, decimal newValue) : base(routedEvent)
+        public NumericUpDownValueChangedEventArgs(RoutedEvent routedEvent, decimal? oldValue, decimal? newValue) : base(routedEvent)
         {
             OldValue = oldValue;
             NewValue = newValue;
         }
 
-        public decimal OldValue { get; }
-        public decimal NewValue { get; }
+        public decimal? OldValue { get; }
+        public decimal? NewValue { get; }
     }
 }

src/Avalonia.Controls/Presenters/CarouselPresenter.cs

@@ -31,7 +31,7 @@ namespace Avalonia.Controls.Presenters
         /// <summary>
         /// Defines the <see cref="PageTransition"/> property.
         /// </summary>
-        public static readonly StyledProperty<IPageTransition> PageTransitionProperty =
+        public static readonly StyledProperty<IPageTransition?> PageTransitionProperty =
             Carousel.PageTransitionProperty.AddOwner<CarouselPresenter>();
 
         private int _selectedIndex = -1;
@@ -85,7 +85,7 @@ namespace Avalonia.Controls.Presenters
         /// <summary>
         /// Gets or sets a transition to use when switching pages.
         /// </summary>
-        public IPageTransition PageTransition
+        public IPageTransition? PageTransition
         {
             get { return GetValue(PageTransitionProperty); }
             set { SetValue(PageTransitionProperty, value); }

src/Avalonia.Themes.Default/SimpleTheme.cs

@@ -44,7 +44,7 @@ namespace Avalonia.Themes.Default
             InitStyles(_baseUri);
         }
 
-        public event EventHandler OwnerChanged
+        public event EventHandler? OwnerChanged
         {
             add
             {

src/Avalonia.Themes.Fluent/FluentTheme.cs

@@ -50,7 +50,9 @@ namespace Avalonia.Themes.Fluent
         /// <param name="serviceProvider">The XAML service provider.</param>
         public FluentTheme(IServiceProvider serviceProvider)
         {
-            _baseUri = ((IUriContext)serviceProvider.GetService(typeof(IUriContext))).BaseUri;
+            var ctx  = serviceProvider.GetService(typeof(IUriContext)) as IUriContext
+                 ?? throw new NullReferenceException("Unable retrive UriContext");
+            _baseUri = ctx.BaseUri;
             InitStyles(_baseUri);
         }
 
@@ -81,6 +83,14 @@ namespace Avalonia.Themes.Fluent
         protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
         {
             base.OnPropertyChanged(change);
+            
+            if (_loaded is null)
+            {
+                // If style wasn't yet loaded, no need to change children styles,
+                // it will be applied later in Loaded getter.
+                return;
+            }
+            
             if (change.Property == ModeProperty)
             {
                 if (Mode == FluentThemeMode.Dark)
@@ -146,7 +156,7 @@ namespace Avalonia.Themes.Fluent
 
         IReadOnlyList<IStyle> IStyle.Children => _loaded?.Children ?? Array.Empty<IStyle>();
 
-        public event EventHandler OwnerChanged
+        public event EventHandler? OwnerChanged
         {
             add
             {

src/Avalonia.X11/X11Atoms.cs

@@ -155,6 +155,7 @@ namespace Avalonia.X11
         public readonly IntPtr _NET_FRAME_EXTENTS;
         public readonly IntPtr _NET_WM_PING;
         public readonly IntPtr _NET_WM_SYNC_REQUEST;
+        public readonly IntPtr _NET_WM_SYNC_REQUEST_COUNTER;
         public readonly IntPtr _NET_SYSTEM_TRAY_S;
         public readonly IntPtr _NET_SYSTEM_TRAY_ORIENTATION;
         public readonly IntPtr _NET_SYSTEM_TRAY_OPCODE;

src/Avalonia.X11/X11Info.cs

@@ -33,6 +33,7 @@ namespace Avalonia.X11
         public IntPtr LastActivityTimestamp { get; set; }
         public XVisualInfo? TransparentVisualInfo { get; set; }
         public bool HasXim { get; set; }
+        public bool HasXSync { get; set; }
         public IntPtr DefaultFontSet { get; set; }
         
         public unsafe X11Info(IntPtr display, IntPtr deferredDisplay, bool useXim)
@@ -101,6 +102,15 @@ namespace Avalonia.X11
             {
                 //Ignore, XI is not supported
             }
+
+            try
+            {
+                HasXSync = XSyncInitialize(display, out _, out _) != Status.Success;
+            }
+            catch
+            {
+                //Ignore, XSync is not supported
+            }
         }
     }
 }

src/Avalonia.X11/X11Window.cs

@@ -45,6 +45,8 @@ namespace Avalonia.X11
         private IntPtr _handle;
         private IntPtr _xic;
         private IntPtr _renderHandle;
+        private IntPtr _xSyncCounter;
+        private XSyncValue _xSyncValue;
         private bool _mapped;
         private bool _wasMappedAtLeastOnce = false;
         private double? _scalingOverride;
@@ -190,6 +192,16 @@ namespace Avalonia.X11
                 NativeMenuExporter = DBusMenuExporter.TryCreateTopLevelNativeMenu(_handle);
             NativeControlHost = new X11NativeControlHost(_platform, this);
             InitializeIme();
+            
+            XChangeProperty(_x11.Display, _handle, _x11.Atoms.WM_PROTOCOLS, _x11.Atoms.XA_ATOM, 32,
+                PropertyMode.Replace, new[] { _x11.Atoms.WM_DELETE_WINDOW, _x11.Atoms._NET_WM_SYNC_REQUEST }, 2);
+
+            if (_x11.HasXSync)
+            {
+                _xSyncCounter = XSyncCreateCounter(_x11.Display, _xSyncValue);
+                XChangeProperty(_x11.Display, _handle, _x11.Atoms._NET_WM_SYNC_REQUEST_COUNTER,
+                    _x11.Atoms.XA_CARDINAL, 32, PropertyMode.Replace, ref _xSyncCounter, 1);
+            }
         }
 
         class SurfaceInfo  : EglGlPlatformSurface.IEglWindowGlPlatformSurfaceInfo
@@ -383,15 +395,7 @@ namespace Avalonia.X11
                      (ev.type == XEventName.VisibilityNotify &&
                       ev.VisibilityEvent.state < 2))
             {
-                if (!_triggeredExpose)
-                {
-                    _triggeredExpose = true;
-                    Dispatcher.UIThread.Post(() =>
-                    {
-                        _triggeredExpose = false;
-                        DoPaint();
-                    }, DispatcherPriority.Render);
-                }
+                EnqueuePaint();
             }
             else if (ev.type == XEventName.FocusIn)
             {
@@ -503,6 +507,7 @@ namespace Avalonia.X11
                 if (_useRenderWindow)
                     XConfigureResizeWindow(_x11.Display, _renderHandle, ev.ConfigureEvent.width,
                         ev.ConfigureEvent.height);
+                EnqueuePaint();
             }
             else if (ev.type == XEventName.DestroyNotify 
                      && ev.DestroyWindowEvent.window == _handle)
@@ -518,7 +523,11 @@ namespace Avalonia.X11
                         if (Closing?.Invoke() != true)
                             Dispose();
                     }
-
+                    else if (ev.ClientMessageEvent.ptr1 == _x11.Atoms._NET_WM_SYNC_REQUEST)
+                    {
+                        _xSyncValue.Lo = new UIntPtr(ev.ClientMessageEvent.ptr3.ToPointer()).ToUInt32();
+                        _xSyncValue.Hi = ev.ClientMessageEvent.ptr4.ToInt32();
+                    }
                 }
             }
             else if (ev.type == XEventName.KeyPress || ev.type == XEventName.KeyRelease)
@@ -730,9 +739,24 @@ namespace Avalonia.X11
             ScheduleInput(mev, ref ev);
         }
 
+        void EnqueuePaint()
+        {
+            if (!_triggeredExpose)
+            {
+                _triggeredExpose = true;
+                Dispatcher.UIThread.Post(() =>
+                {
+                    _triggeredExpose = false;
+                    DoPaint();
+                }, DispatcherPriority.Render);
+            }
+        }
+        
         void DoPaint()
         {
             Paint?.Invoke(new Rect());
+            if (_xSyncCounter != IntPtr.Zero)
+                XSyncSetCounter(_x11.Display, _xSyncCounter, _xSyncValue);
         }
         
         public void Invalidate(Rect rect)
@@ -1160,7 +1184,7 @@ namespace Avalonia.X11
             }
 
             public IntPtr Handle => _owner._renderHandle;
-            public string? HandleDescriptor => "XID";
+            public string HandleDescriptor => "XID";
         }
     }
 }

src/Avalonia.X11/XLib.cs

@@ -542,6 +542,18 @@ namespace Avalonia.X11
         public static extern int XRRQueryExtension (IntPtr dpy,
             out int event_base_return,
             out int error_base_return);
+        
+        [DllImport(libX11Ext)]
+        public static extern Status XSyncInitialize(IntPtr dpy, out int event_base_return, out int error_base_return);
+
+        [DllImport(libX11Ext)]
+        public static extern IntPtr XSyncCreateCounter(IntPtr dpy, XSyncValue initialValue);
+        
+        [DllImport(libX11Ext)]
+        public static extern int XSyncDestroyCounter(IntPtr dpy, IntPtr counter);
+        
+        [DllImport(libX11Ext)]
+        public static extern int XSyncSetCounter(IntPtr dpy, IntPtr counter, XSyncValue value);
 
         [DllImport(libX11Randr)]
         public static extern int XRRQueryVersion(IntPtr dpy,
@@ -627,6 +639,11 @@ namespace Avalonia.X11
             public int bw;
             public int d;
         }
+        
+        public struct XSyncValue {
+            public int Hi;
+            public uint Lo;
+        }
 
         public static bool XGetGeometry(IntPtr display, IntPtr window, out XGeometry geo)
         {

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/PropertyInfoAccessorFactory.cs

@@ -1,8 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
-using System.Text;
 using Avalonia.Data;
 using Avalonia.Data.Core;
 using Avalonia.Data.Core.Plugins;
@@ -174,7 +172,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
                 WeakEvents.CollectionChanged.Unsubscribe(incc, this);
         }
         
-        public void OnEvent(object? sender, WeakEvent ev, NotifyCollectionChangedEventArgs args)
+        public void OnEvent(object sender, WeakEvent ev, NotifyCollectionChangedEventArgs args)
         {
             if (ShouldNotifyListeners(args))
             {

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/ResourceInclude.cs

@@ -42,7 +42,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
 
         bool IResourceNode.HasResources => Loaded.HasResources;
 
-        public event EventHandler OwnerChanged
+        public event EventHandler? OwnerChanged
         {
             add => Loaded.OwnerChanged += value;
             remove => Loaded.OwnerChanged -= value;
@@ -52,7 +52,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
         {
             if (!_isLoading)
             {
-                return Loaded.TryGetResource(key, out value);                
+                return Loaded.TryGetResource(key, out value);
             }
 
             value = null;

src/Markup/Avalonia.Markup.Xaml/Styling/StyleInclude.cs

@@ -64,7 +64,7 @@ namespace Avalonia.Markup.Xaml.Styling
 
         IReadOnlyList<IStyle> IStyle.Children => _loaded ?? Array.Empty<IStyle>();
 
-        public event EventHandler OwnerChanged
+        public event EventHandler? OwnerChanged
         {
             add
             {

src/Web/Avalonia.Web.Blazor/AvaloniaView.razor

@@ -1,24 +1,26 @@
 <div id="container" class="avalonia-container" tabindex="0" oncontextmenu="return false;"
-     ontouchcancel="@OnTouchCancel"
-     ontouchmove="@OnTouchMove"
-     onwheel="@OnWheel"
-     onkeydown="@OnKeyDown"
-     onkeyup="@OnKeyUp"
-     onpointerdown="@OnPointerDown"
-     onpointerup="@OnPointerUp"
-     onpointermove="@OnPointerMove">
+     @onwheel="OnWheel"
+     @onkeydown="OnKeyDown"
+     @onkeyup="OnKeyUp"
+     @onpointerdown="OnPointerDown"
+     @onpointerup="OnPointerUp"
+     @onpointermove="OnPointerMove"
+     @onpointercancel="OnPointerCancel">
     
     <canvas id="htmlCanvas" @ref="_htmlCanvas" @attributes="AdditionalAttributes"/>
 
 	<div id="nativeControlsContainer" @ref="_nativeControlsContainer" />
 
-    <input id="inputElement" @ref="_inputElement" type="text" oninput="@OnInput" 
+    <input id="inputElement" @ref="_inputElement" type="text" @oninput="OnInput" 
         onpaste="return false;"
         oncopy="return false;" 
         oncut="return false;"/>
 </div>
 
 <style>
+#container{
+    touch-action: none;
+}
 #htmlCanvas {
     opacity: 1;
     background-color: #ccc;

src/Web/Avalonia.Web.Blazor/AvaloniaView.razor.cs

@@ -57,27 +57,23 @@ namespace Avalonia.Web.Blazor
             return _nativeControlHost ?? throw new InvalidOperationException("Blazor View wasn't initialized yet");
         }
         
-        private void OnTouchCancel(TouchEventArgs e)
+        private void OnPointerCancel(Microsoft.AspNetCore.Components.Web.PointerEventArgs e)
         {
-            foreach (var touch in e.ChangedTouches)
+            if (e.PointerType == "touch")
             {
-                _topLevelImpl.RawTouchEvent(RawPointerEventType.TouchCancel, new Point(touch.ClientX, touch.ClientY),
-                    GetModifiers(e), touch.Identifier);
+                _topLevelImpl.RawTouchEvent(RawPointerEventType.TouchCancel, new Point(e.ClientX, e.ClientY),
+                    GetModifiers(e), e.PointerId);
             }
         }
 
-        private void OnTouchMove(TouchEventArgs e)
+        private void OnPointerMove(Microsoft.AspNetCore.Components.Web.PointerEventArgs e)
         {
-            foreach (var touch in e.ChangedTouches)
+            if (e.PointerType == "touch")
             {
-                _topLevelImpl.RawTouchEvent(RawPointerEventType.TouchUpdate, new Point(touch.ClientX, touch.ClientY),
-                    GetModifiers(e), touch.Identifier);
+                _topLevelImpl.RawTouchEvent(RawPointerEventType.TouchUpdate, new Point(e.ClientX, e.ClientY),
+                    GetModifiers(e), e.PointerId);
             }
-        }
-
-        private void OnPointerMove(Microsoft.AspNetCore.Components.Web.PointerEventArgs e)
-        {
-            if (e.PointerType != "touch")
+            else
             {
                 _topLevelImpl.RawMouseEvent(RawPointerEventType.Move, new Point(e.ClientX, e.ClientY), GetModifiers(e));
             }
@@ -174,22 +170,6 @@ namespace Avalonia.Web.Blazor
             return modifiers;
         }
 
-        private static RawInputModifiers GetModifiers(TouchEventArgs e)
-        {
-            var modifiers = RawInputModifiers.None;
-
-            if (e.CtrlKey)
-                modifiers |= RawInputModifiers.Control;
-            if (e.AltKey)
-                modifiers |= RawInputModifiers.Alt;
-            if (e.ShiftKey)
-                modifiers |= RawInputModifiers.Shift;
-            if (e.MetaKey)
-                modifiers |= RawInputModifiers.Meta;
-
-            return modifiers;
-        }
-
         private static RawInputModifiers GetModifiers(Microsoft.AspNetCore.Components.Web.PointerEventArgs e)
         {
             var modifiers = RawInputModifiers.None;

src/Windows/Avalonia.Win32/Automation/RootAutomationNode.cs

@@ -42,7 +42,7 @@ namespace Avalonia.Win32.Automation
             return GetOrCreate(focus);
         }
 
-        public void FocusChanged(object sender, EventArgs e)
+        public void FocusChanged(object? sender, EventArgs e)
         {
             RaiseFocusChanged(GetOrCreate(Peer.GetFocus()));
         }

src/Windows/Avalonia.Win32/Avalonia.Win32.csproj

@@ -18,4 +18,8 @@
   </ItemGroup>
   <Import Project="$(MSBuildThisFileDirectory)\..\..\..\build\System.Drawing.Common.props" />
   <Import Project="..\..\..\build\DevAnalyzers.props" />
+  <PropertyGroup Label="Warnings">
+    <NoWarn Condition="'$(NoWarn)' == ''">CA1416</NoWarn>
+    <NoWarn Condition="'$(NoWarn)' != ''">$(NoWarn),CA1416</NoWarn>
+  </PropertyGroup>
 </Project>

src/Windows/Avalonia.Win32/Interop/Automation/ISelectionItemProvider.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Runtime.InteropServices;
 

src/Windows/Avalonia.Win32/TrayIconImpl.cs

@@ -195,7 +195,7 @@ namespace Avalonia.Win32
                 ShowActivated = true;
             }
 
-            private void TrayPopupRoot_Deactivated(object sender, EventArgs e)
+            private void TrayPopupRoot_Deactivated(object? sender, EventArgs e)
             {
                 Close();
             }

src/Windows/Avalonia.Win32/WindowImpl.CustomCaptionProc.cs

@@ -109,7 +109,7 @@ namespace Avalonia.Win32
 
                             if (_owner is Window window)
                             {
-                                var visual = window.Renderer.HitTestFirst(position, _owner as Window, x =>
+                                var visual = window.Renderer.HitTestFirst(position, _owner, x =>
                                 {
                                     if (x is IInputElement ie && (!ie.IsHitTestVisible || !ie.IsVisible))
                                     {

tests/Avalonia.Base.UnitTests/Media/MatrixTests.cs

@@ -30,6 +30,16 @@ namespace Avalonia.Base.UnitTests.Media
             Assert.True(matrix.HasInverse);
         }
 
+        [Fact]
+        public void Invert_Should_Work()
+        {
+            var matrix = new Matrix(1, 2, 3, 0, 1, 4, 5, 6, 0);
+            var inverted = matrix.Invert();
+
+            Assert.Equal(matrix * inverted, Matrix.Identity);
+            Assert.Equal(inverted * matrix, Matrix.Identity);
+        }
+
         [Fact]
         public void Can_Decompose_Translation()
         {

tests/Avalonia.Benchmarks/TestBindingObservable.cs

@@ -1,4 +1,5 @@
-using System;
+#nullable enable
+using System;
 using Avalonia.Data;
 
 namespace Avalonia.Benchmarks

tests/Avalonia.Controls.UnitTests/ButtonTests.cs

@@ -309,6 +309,80 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal(0, raised);
         }
+        
+        [Fact]
+        public void Button_IsDefault_Works()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var raised = 0;
+                var target = new Button();
+                var window = new Window { Content = target };
+                window.Show();
+                
+                target.Click += (s, e) => ++raised;
+
+                target.IsDefault = false;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
+                Assert.Equal(0, raised);
+                
+                target.IsDefault = true;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
+                Assert.Equal(1, raised);
+
+                target.IsDefault = false;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
+                Assert.Equal(1, raised);
+                
+                target.IsDefault = true;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Enter));
+                Assert.Equal(2, raised);
+                
+                window.Content = null;
+                // To check if handler was raised on the button, when it's detached, we need to pass it as a source manually.
+                window.RaiseEvent(CreateKeyDownEvent(Key.Enter, target));
+                Assert.Equal(2, raised);
+            }
+        }
+        
+        [Fact]
+        public void Button_IsCancel_Works()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var raised = 0;
+                var target = new Button();
+                var window = new Window { Content = target };
+                window.Show();
+                
+                target.Click += (s, e) => ++raised;
+
+                target.IsCancel = false;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
+                Assert.Equal(0, raised);
+                
+                target.IsCancel = true;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
+                Assert.Equal(1, raised);
+
+                target.IsCancel = false;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
+                Assert.Equal(1, raised);
+                
+                target.IsCancel = true;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Escape));
+                Assert.Equal(2, raised);
+                
+                window.Content = null;
+                window.RaiseEvent(CreateKeyDownEvent(Key.Escape, target));
+                Assert.Equal(2, raised);
+            }
+        }
+
+        private KeyEventArgs CreateKeyDownEvent(Key key, IInteractive source = null)
+        {
+            return new KeyEventArgs { RoutedEvent = InputElement.KeyDownEvent, Key = key, Source = source };
+        }
 
         private class TestButton : Button, IRenderRoot
         {

tests/Avalonia.RenderTests/Media/GeometryDrawingTests.cs

@@ -0,0 +1,52 @@
+using Avalonia.Media;
+using Xunit;
+
+#if AVALONIA_SKIA
+namespace Avalonia.Skia.RenderTests
+#else
+
+using Avalonia.Direct2D1.RenderTests;
+
+namespace Avalonia.Direct2D1.RenderTests.Media
+#endif
+{
+    public class GeometryDrawingTests : TestBase
+    {
+        public GeometryDrawingTests()
+            : base(@"Media\GeometryDrawing")
+        {
+        }
+
+        private GeometryDrawing CreateGeometryDrawing()
+        {
+            GeometryDrawing geometryDrawing = new GeometryDrawing();
+            EllipseGeometry ellipse = new EllipseGeometry();
+            ellipse.RadiusX = 100;
+            ellipse.RadiusY = 100;
+            geometryDrawing.Geometry = ellipse;
+            return geometryDrawing;
+        }
+
+        [Fact]
+        public void DrawingGeometry_WithPen()
+        {
+            GeometryDrawing geometryDrawing = CreateGeometryDrawing();
+            geometryDrawing.Pen = new Pen(new SolidColorBrush(Color.FromArgb(255, 0, 0, 0)), 10);
+
+            Assert.Equal(210, geometryDrawing.GetBounds().Height);
+            Assert.Equal(210, geometryDrawing.GetBounds().Width);
+
+        }
+
+        [Fact]
+        public void DrawingGeometry_WithoutPen()
+        {
+            GeometryDrawing geometryDrawing = CreateGeometryDrawing();
+
+            Assert.Equal(200, geometryDrawing.GetBounds().Height);
+            Assert.Equal(200, geometryDrawing.GetBounds().Width);
+        }
+
+
+    }
+}

tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextFormatterTests.cs

@@ -602,7 +602,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
 
         private class EndOfLineTextSource : ITextSource
         {
-            public TextRun? GetTextRun(int textSourceIndex)
+            public TextRun GetTextRun(int textSourceIndex)
             {
                 return new TextEndOfLine();
             }
@@ -617,7 +617,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
                 _text = text;
             }
             
-            public TextRun? GetTextRun(int textSourceIndex)
+            public TextRun GetTextRun(int textSourceIndex)
             {
                 if (textSourceIndex >= _text.Length + TextRun.DefaultTextSourceLength + _text.Length)
                 {

tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextLineTests.cs

@@ -639,7 +639,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
         {
             const string Text = "_A_A";
 
-            public TextRun? GetTextRun(int textSourceIndex)
+            public TextRun GetTextRun(int textSourceIndex)
             {
                 switch (textSourceIndex)
                 {
@@ -907,7 +907,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
                 _textRuns = textRuns;
             }
 
-            public TextRun? GetTextRun(int textSourceIndex)
+            public TextRun GetTextRun(int textSourceIndex)
             {
                 var currentPosition = 0;