Merge branch 'master' into feature/tabindex

.gitignore

@@ -106,6 +106,9 @@ _NCrunch_*/
 *.ncrunchsolution.user
 nCrunchTemp_*
 
+# CodeRush
+.cr/
+
 # Others
 sql/
 *.Cache

native/Avalonia.Native/inc/comimpl.h

@@ -8,8 +8,109 @@
 
 #include <cstring>
 
+/**
+ START_COM_CALL causes AddRef to be called at the beggining of a function.
+ When a function is exited, it causes ReleaseRef to be called.
+ This ensures that the object cannot be destroyed whilst the function is running.
+ For example: Window Show is called, which triggers an event, and user calls Close inside the event
+ causing the refcount to reach 0, and the object to be destroyed. Function then continues and this pointer
+ will now be invalid.
+ 
+ START_COM_CALL protects against this scenario.
+ */
+#define START_COM_CALL auto r = this->UnknownSelf()
+
 __IID_DEF(IUnknown, 0, 0, 0, C0, 00, 00, 00, 00, 00, 00, 46);
 
+template<class TInterface>
+class ComPtr
+{
+private:
+    TInterface* _obj;
+public:
+    ComPtr()
+    {
+        _obj = 0;
+    }
+    
+    ComPtr(TInterface* pObj)
+    {
+        _obj = 0;
+
+        if (pObj)
+        {
+            _obj = pObj;
+            _obj->AddRef();
+        }
+    }
+    
+    ComPtr(const ComPtr& ptr)
+    {
+        _obj = 0;
+        
+        if (ptr._obj)
+        {
+            _obj = ptr._obj;
+            _obj->AddRef();
+        }
+
+    }
+    
+    ComPtr& operator=(ComPtr other)
+    {
+        if(_obj != NULL)
+            _obj->Release();
+        _obj = other._obj;
+        if(_obj != NULL)
+            _obj->AddRef();
+        return *this;
+    }
+
+    ~ComPtr()
+    {
+        if (_obj)
+        {
+            _obj->Release();
+            _obj = 0;
+        }
+    }
+    
+    TInterface* getRaw()
+    {
+        return _obj;
+    }
+    
+    TInterface* getRetainedReference()
+    {
+        if(_obj == NULL)
+            return NULL;
+        _obj->AddRef();
+        return _obj;
+    }
+    
+    TInterface** getPPV()
+    {
+        return &_obj;
+    }
+    
+    operator TInterface*() const
+    {
+        return _obj;
+    }
+    TInterface& operator*() const
+    {
+        return *_obj;
+    }
+    TInterface** operator&()
+    {
+        return &_obj;
+    }
+    TInterface* operator->() const
+    {
+        return _obj;
+    }
+};
+
 class ComObject : public virtual IUnknown
 {
 private:
@@ -58,6 +159,12 @@ public:
         _refCount++;
         return S_OK;
     }
+    
+protected:
+   ComPtr<IUnknown> UnknownSelf()
+    {
+       return this;
+   }
 
 };
 
@@ -104,94 +211,5 @@ public:
     virtual ~ComSingleObject(){}
 };
 
-template<class TInterface>
-class ComPtr
-{
-private:
-    TInterface* _obj;
-public:
-    ComPtr()
-    {
-        _obj = 0;
-    }
-    
-    ComPtr(TInterface* pObj)
-    {
-        _obj = 0;
-
-        if (pObj)
-        {
-            _obj = pObj;
-            _obj->AddRef();
-        }
-    }
-    
-    ComPtr(const ComPtr& ptr)
-    {
-        _obj = 0;
-        
-        if (ptr._obj)
-        {
-            _obj = ptr._obj;
-            _obj->AddRef();
-        }
-
-    }
-    
-    ComPtr& operator=(ComPtr other)
-    {
-        if(_obj != NULL)
-            _obj->Release();
-        _obj = other._obj;
-        if(_obj != NULL)
-            _obj->AddRef();
-        return *this;
-    }
-
-    ~ComPtr()
-    {
-        if (_obj)
-        {
-            _obj->Release();
-            _obj = 0;
-        }
-    }
-    
-    TInterface* getRaw()
-    {
-        return _obj;
-    }
-    
-    TInterface* getRetainedReference()
-    {
-        if(_obj == NULL)
-            return NULL;
-        _obj->AddRef();
-        return _obj;
-    }
-    
-    TInterface** getPPV()
-    {
-        return &_obj;
-    }
-    
-    operator TInterface*() const
-    {
-        return _obj;
-    }
-    TInterface& operator*() const
-    {
-        return *_obj;
-    }
-    TInterface** operator&()
-    {
-        return &_obj;
-    }
-    TInterface* operator->() const
-    {
-        return _obj;
-    }
-};
-
 #endif // COMIMPL_H_INCLUDED
 #pragma clang diagnostic pop

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

@@ -43,6 +43,8 @@ public:
     
     virtual HRESULT Pointer(void**retOut) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(retOut == nullptr)
@@ -58,14 +60,19 @@ public:
     
     virtual HRESULT Length(int*retOut) override
     {
-        if(retOut == nullptr)
+        START_COM_CALL;
+        
+        @autoreleasepool
         {
-            return E_POINTER;
+            if(retOut == nullptr)
+            {
+                return E_POINTER;
+            }
+            
+            *retOut = _length;
+            
+            return S_OK;
         }
-        
-        *retOut = _length;
-        
-        return S_OK;
     }
 };
 
@@ -109,10 +116,15 @@ public:
     
     virtual HRESULT Get(unsigned int index, IAvnString**ppv) override
     {
-        if(_list.size() <= index)
-            return E_INVALIDARG;
-        *ppv = _list[index].getRetainedReference();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            if(_list.size() <= index)
+                return E_INVALIDARG;
+            *ppv = _list[index].getRetainedReference();
+            return S_OK;
+        }
     }
 };
 

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

@@ -8,6 +8,8 @@ class Screens : public ComSingleObject<IAvnScreens, &IID_IAvnScreens>
 public:
     virtual HRESULT GetScreenCount (int* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             *ret = (int)[NSScreen screens].count;
@@ -18,6 +20,8 @@ public:
     
     virtual HRESULT GetScreen (int index, AvnScreen* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(index < 0 || index >= [NSScreen screens].count)

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

@@ -50,6 +50,12 @@ ComPtr<IAvnApplicationEvents> _events;
     
     _events->FilesOpened(array);
 }
+
+- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
+{
+    return _events->TryShutdown() ? NSTerminateNow : NSTerminateCancel;
+}
+
 @end
 
 @interface AvnApplication : NSApplication

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

@@ -69,6 +69,8 @@ public:
     
     virtual HRESULT LegacyMakeCurrent() override
     {
+        START_COM_CALL;
+        
         if(CGLSetCurrentContext(Context) != 0)
             return E_FAIL;
         return S_OK;
@@ -76,6 +78,8 @@ public:
     
     virtual HRESULT MakeCurrent(IUnknown** ppv) override
     {
+        START_COM_CALL;
+        
         CGLContextObj saved = CGLGetCurrentContext();
         CGLLockContext(Context);
         if(CGLSetCurrentContext(Context) != 0)
@@ -128,6 +132,8 @@ public:
     
     virtual HRESULT CreateContext(IAvnGlContext* share, IAvnGlContext**ppv) override
     {
+        START_COM_CALL;
+        
         CGLContextObj shareContext = nil;
         if(share != nil)
         {
@@ -144,6 +150,8 @@ public:
     
     virtual HRESULT WrapContext(void* native, IAvnGlContext**ppv) override
     {
+        START_COM_CALL;
+        
         if(native == nil)
             return E_INVALIDARG;
         *ppv = new AvnGlContext((CGLContextObj) native);

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

@@ -25,6 +25,8 @@ public:
    
     virtual HRESULT GetText (char* type, IAvnString**ppv) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ppv == nullptr)
@@ -42,6 +44,8 @@ public:
     
     virtual HRESULT GetStrings(char* type, IAvnStringArray**ppv) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             *ppv= nil;
@@ -69,56 +73,71 @@ public:
     
     virtual HRESULT SetText (char* type, char* utf8String) override
     {
-        Clear();
+        START_COM_CALL;
+        
         @autoreleasepool
         {
+            Clear();
+            
             auto string = [NSString stringWithUTF8String:(const char*)utf8String];
             auto typeString = [NSString stringWithUTF8String:(const char*)type];
             if(_item == nil)
                 [_pb setString: string forType: typeString];
             else
                 [_item setString: string forType:typeString];
-        }
         
-        return S_OK;
+            return S_OK;
+        }
     }
     
     virtual HRESULT SetBytes(char* type, void* bytes, int len) override
     {
-        auto typeString = [NSString stringWithUTF8String:(const char*)type];
-        auto data = [NSData dataWithBytes:bytes length:len];
-        if(_item == nil)
-            [_pb setData:data forType:typeString];
-        else
-            [_item setData:data forType:typeString];
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            auto typeString = [NSString stringWithUTF8String:(const char*)type];
+            auto data = [NSData dataWithBytes:bytes length:len];
+            if(_item == nil)
+                [_pb setData:data forType:typeString];
+            else
+                [_item setData:data forType:typeString];
+            return S_OK;
+        }
     }
        
     virtual HRESULT GetBytes(char* type, IAvnString**ppv) override
     {
-        *ppv = nil;
-        auto typeString = [NSString stringWithUTF8String:(const char*)type];
-        NSData*data;
-        @try
+        START_COM_CALL;
+        
+        @autoreleasepool
         {
-            if(_item)
-                data = [_item dataForType:typeString];
-            else
-                data = [_pb dataForType:typeString];
-            if(data == nil)
+            *ppv = nil;
+            auto typeString = [NSString stringWithUTF8String:(const char*)type];
+            NSData*data;
+            @try
+            {
+                if(_item)
+                    data = [_item dataForType:typeString];
+                else
+                    data = [_pb dataForType:typeString];
+                if(data == nil)
+                    return E_FAIL;
+            }
+            @catch(NSException* e)
+            {
                 return E_FAIL;
+            }
+            *ppv = CreateByteArray((void*)data.bytes, (int)data.length);
+            return S_OK;
         }
-        @catch(NSException* e)
-        {
-            return E_FAIL;
-        }
-        *ppv = CreateByteArray((void*)data.bytes, (int)data.length);
-        return S_OK;
     }
 
 
     virtual HRESULT Clear() override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(_item != nil)
@@ -128,15 +147,20 @@ public:
                 [_pb clearContents];
                 [_pb setString:@"" forType:NSPasteboardTypeString];
             }
-        }
         
-        return S_OK;
+            return S_OK;
+        }
     }
     
     virtual HRESULT ObtainFormats(IAvnStringArray** ppv) override
     {
-        *ppv = CreateAvnStringArray(_item == nil ? [_pb types] : [_item types]);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = CreateAvnStringArray(_item == nil ? [_pb types] : [_item types]);
+            return S_OK;
+        }
     }
 };
 

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

@@ -16,11 +16,16 @@ public:
     
     virtual HRESULT CreateDefaultChild(void* parent, void** retOut) override
     {
-        NSView* view = [NSView new];
-        [view setWantsLayer: true];
+        START_COM_CALL;
         
-        *retOut = (__bridge_retained void*)view;
-        return S_OK;
+        @autoreleasepool
+        {
+            NSView* view = [NSView new];
+            [view setWantsLayer: true];
+            
+            *retOut = (__bridge_retained void*)view;
+            return S_OK;
+        }
     };
     
     virtual IAvnNativeControlHostTopLevelAttachment* CreateAttachment() override
@@ -69,32 +74,42 @@ public:
     
     virtual HRESULT InitializeWithChildHandle(void* child) override
     {
-        if(_child != nil)
-            return E_FAIL;
-        _child = (__bridge NSView*)child;
-        if(_child == nil)
-            return E_FAIL;
-        [_holder addSubview:_child];
-        [_child setHidden: false];
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            if(_child != nil)
+                return E_FAIL;
+            _child = (__bridge NSView*)child;
+            if(_child == nil)
+                return E_FAIL;
+            [_holder addSubview:_child];
+            [_child setHidden: false];
+            return S_OK;
+        }
     };
     
     virtual HRESULT AttachTo(IAvnNativeControlHost* host) override
     {
-        if(host == nil)
-        {
-            [_holder removeFromSuperview];
-            [_holder setHidden: true];
-        }
-        else
+        START_COM_CALL;
+        
+        @autoreleasepool
         {
-            AvnNativeControlHost* chost = dynamic_cast<AvnNativeControlHost*>(host);
-            if(chost == nil || chost->View == nil)
-                return E_FAIL;
-            [_holder setHidden:true];
-            [chost->View addSubview:_holder];
+            if(host == nil)
+            {
+                [_holder removeFromSuperview];
+                [_holder setHidden: true];
+            }
+            else
+            {
+                AvnNativeControlHost* chost = dynamic_cast<AvnNativeControlHost*>(host);
+                if(chost == nil || chost->View == nil)
+                    return E_FAIL;
+                [_holder setHidden:true];
+                [chost->View addSubview:_holder];
+            }
+            return S_OK;
         }
-        return S_OK;
     };
     
     virtual void ShowInBounds(float x, float y, float width, float height) override

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

@@ -53,36 +53,46 @@ public:
     
     virtual HRESULT GetCursor (AvnStandardCursorType cursorType, IAvnCursor** retOut) override
     {
-        *retOut = s_cursorMap[cursorType];
+        START_COM_CALL;
         
-        if(*retOut != nullptr)
+        @autoreleasepool
         {
-            (*retOut)->AddRef();
-        }
+            *retOut = s_cursorMap[cursorType];
             
-        return S_OK;
+            if(*retOut != nullptr)
+            {
+                (*retOut)->AddRef();
+            }
+                
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateCustomCursor (void* bitmapData, size_t length, AvnPixelSize hotPixel, IAvnCursor** retOut) override
     {
-        if(bitmapData == nullptr || retOut == nullptr)
+        START_COM_CALL;
+        
+        @autoreleasepool
         {
-            return E_POINTER;
+            if(bitmapData == nullptr || retOut == nullptr)
+            {
+                return E_POINTER;
+            }
+            
+            NSData *imageData = [NSData dataWithBytes:bitmapData length:length];
+            NSImage *image = [[NSImage alloc] initWithData:imageData];
+            
+            
+            NSPoint hotSpot;
+            hotSpot.x = hotPixel.Width;
+            hotSpot.y = hotPixel.Height;
+            
+            *retOut = new Cursor([[NSCursor new] initWithImage: image hotSpot: hotSpot]);
+            
+            (*retOut)->AddRef();
+            
+            return S_OK;
         }
-        
-        NSData *imageData = [NSData dataWithBytes:bitmapData length:length];
-        NSImage *image = [[NSImage alloc] initWithData:imageData];
-        
-        
-        NSPoint hotSpot;
-        hotSpot.x = hotPixel.Width;
-        hotSpot.y = hotPixel.Height;
-        
-        *retOut = new Cursor([[NSCursor new] initWithImage: image hotSpot: hotSpot]);
-        
-        (*retOut)->AddRef();
-        
-        return S_OK;
     }
 };
 

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

@@ -107,27 +107,42 @@ public:
     
     virtual HRESULT SetApplicationTitle(char* utf8String) override
     {
-        auto appTitle = [NSString stringWithUTF8String: utf8String];
+        START_COM_CALL;
         
-        [[NSProcessInfo processInfo] setProcessName:appTitle];
-        
-        
-        SetProcessName(appTitle);
-        
-        return S_OK;
+        @autoreleasepool
+        {
+            auto appTitle = [NSString stringWithUTF8String: utf8String];
+            
+            [[NSProcessInfo processInfo] setProcessName:appTitle];
+            
+            
+            SetProcessName(appTitle);
+            
+            return S_OK;
+        }
     }
     
     virtual HRESULT SetShowInDock(int show)  override
     {
-        AvnDesiredActivationPolicy = show
-            ? NSApplicationActivationPolicyRegular : NSApplicationActivationPolicyAccessory;
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            AvnDesiredActivationPolicy = show
+                ? NSApplicationActivationPolicyRegular : NSApplicationActivationPolicyAccessory;
+            return S_OK;
+        }
     }
     
     virtual HRESULT SetDisableDefaultApplicationMenuItems (bool enabled) override
     {
-        SetAutoGenerateDefaultAppMenuItems(!enabled);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            SetAutoGenerateDefaultAppMenuItems(!enabled);
+            return S_OK;
+        }
     }
 };
 
@@ -165,6 +180,8 @@ public:
     FORWARD_IUNKNOWN()
     virtual HRESULT Initialize(IAvnGCHandleDeallocatorCallback* deallocator, IAvnApplicationEvents* events) override
     {
+        START_COM_CALL;
+        
         _deallocator = deallocator;
         @autoreleasepool{
             [[ThreadingInitializer new] do];
@@ -180,89 +197,154 @@ public:
     
     virtual HRESULT CreateWindow(IAvnWindowEvents* cb, IAvnGlContext* gl, IAvnWindow** ppv)  override
     {
-        if(cb == nullptr || ppv == nullptr)
-            return E_POINTER;
-        *ppv = CreateAvnWindow(cb, gl);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            if(cb == nullptr || ppv == nullptr)
+                return E_POINTER;
+            *ppv = CreateAvnWindow(cb, gl);
+            return S_OK;
+        }
     };
     
     virtual HRESULT CreatePopup(IAvnWindowEvents* cb, IAvnGlContext* gl, IAvnPopup** ppv) override
     {
-        if(cb == nullptr || ppv == nullptr)
-            return E_POINTER;
+        START_COM_CALL;
         
-        *ppv = CreateAvnPopup(cb, gl);
-        return S_OK;
+        @autoreleasepool
+        {
+            if(cb == nullptr || ppv == nullptr)
+                return E_POINTER;
+            
+            *ppv = CreateAvnPopup(cb, gl);
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreatePlatformThreadingInterface(IAvnPlatformThreadingInterface** ppv)  override
     {
-        *ppv = CreatePlatformThreading();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = CreatePlatformThreading();
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateSystemDialogs(IAvnSystemDialogs** ppv) override
     {
-        *ppv = ::CreateSystemDialogs();
-        return  S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateSystemDialogs();
+            return  S_OK;
+        }
     }
     
     virtual HRESULT CreateScreens (IAvnScreens** ppv) override
     {
-        *ppv = ::CreateScreens ();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateScreens ();
+            return S_OK;
+        }
     }
 
     virtual HRESULT CreateClipboard(IAvnClipboard** ppv) override
     {
-        *ppv = ::CreateClipboard (nil, nil);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateClipboard (nil, nil);
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateDndClipboard(IAvnClipboard** ppv) override
     {
-        *ppv = ::CreateClipboard (nil, [NSPasteboardItem new]);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateClipboard (nil, [NSPasteboardItem new]);
+            return S_OK;
+        }
     }
 
     virtual HRESULT CreateCursorFactory(IAvnCursorFactory** ppv) override
     {
-        *ppv = ::CreateCursorFactory();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateCursorFactory();
+            return S_OK;
+        }
     }
     
     virtual HRESULT ObtainGlDisplay(IAvnGlDisplay** ppv) override
     {
-        auto rv = ::GetGlDisplay();
-        if(rv == NULL)
-            return E_FAIL;
-        rv->AddRef();
-        *ppv = rv;
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            auto rv = ::GetGlDisplay();
+            if(rv == NULL)
+                return E_FAIL;
+            rv->AddRef();
+            *ppv = rv;
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateMenu (IAvnMenuEvents* cb, IAvnMenu** ppv) override
     {
-        *ppv = ::CreateAppMenu(cb);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateAppMenu(cb);
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateMenuItem (IAvnMenuItem** ppv) override
     {
-        *ppv = ::CreateAppMenuItem();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateAppMenuItem();
+            return S_OK;
+        }
     }
     
     virtual HRESULT CreateMenuItemSeparator (IAvnMenuItem** ppv) override
     {
-        *ppv = ::CreateAppMenuItemSeparator();
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            *ppv = ::CreateAppMenuItemSeparator();
+            return S_OK;
+        }
     }
     
     virtual HRESULT SetAppMenu (IAvnMenu* appMenu) override
     {
-        ::SetAppMenu(s_appTitle, appMenu);
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            ::SetAppMenu(s_appTitle, appMenu);
+            return S_OK;
+        }
     }
 };
 

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

@@ -95,6 +95,8 @@ NSMenuItem* AvnAppMenuItem::GetNative()
 
 HRESULT AvnAppMenuItem::SetSubMenu (IAvnMenu* menu)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if(menu != nullptr)
@@ -114,6 +116,8 @@ HRESULT AvnAppMenuItem::SetSubMenu (IAvnMenu* menu)
 
 HRESULT AvnAppMenuItem::SetTitle (char* utf8String)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if (utf8String != nullptr)
@@ -128,6 +132,8 @@ HRESULT AvnAppMenuItem::SetTitle (char* utf8String)
 
 HRESULT AvnAppMenuItem::SetGesture (AvnKey key, AvnInputModifiers modifiers)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if(key != AvnKeyNone)
@@ -183,6 +189,8 @@ HRESULT AvnAppMenuItem::SetGesture (AvnKey key, AvnInputModifiers modifiers)
 
 HRESULT AvnAppMenuItem::SetAction (IAvnPredicateCallback* predicate, IAvnActionCallback* callback)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         _predicate = predicate;
@@ -193,6 +201,8 @@ HRESULT AvnAppMenuItem::SetAction (IAvnPredicateCallback* predicate, IAvnActionC
 
 HRESULT AvnAppMenuItem::SetIsChecked (bool isChecked)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         [_native setState:(isChecked && _isCheckable ? NSOnState : NSOffState)];
@@ -202,6 +212,8 @@ HRESULT AvnAppMenuItem::SetIsChecked (bool isChecked)
 
 HRESULT AvnAppMenuItem::SetToggleType(AvnMenuItemToggleType toggleType)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         switch(toggleType)
@@ -231,6 +243,8 @@ HRESULT AvnAppMenuItem::SetToggleType(AvnMenuItemToggleType toggleType)
 
 HRESULT AvnAppMenuItem::SetIcon(void *data, size_t length)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if(data != nullptr)
@@ -317,6 +331,8 @@ void AvnAppMenu::RaiseClosed()
 
 HRESULT AvnAppMenu::InsertItem(int index, IAvnMenuItem *item)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if([_native hasGlobalMenuItem])
@@ -337,6 +353,8 @@ HRESULT AvnAppMenu::InsertItem(int index, IAvnMenuItem *item)
 
 HRESULT AvnAppMenu::RemoveItem (IAvnMenuItem* item)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         auto avnMenuItem = dynamic_cast<AvnAppMenuItem*>(item);
@@ -352,6 +370,8 @@ HRESULT AvnAppMenu::RemoveItem (IAvnMenuItem* item)
 
 HRESULT AvnAppMenu::SetTitle (char* utf8String)
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         if (utf8String != nullptr)
@@ -365,6 +385,8 @@ HRESULT AvnAppMenu::SetTitle (char* utf8String)
 
 HRESULT AvnAppMenu::Clear()
 {
+    START_COM_CALL;
+    
     @autoreleasepool
     {
         [_native removeAllItems];

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

@@ -114,6 +114,8 @@ public:
     
     virtual HRESULT RunLoop(IAvnLoopCancellation* cancel) override
     {
+        START_COM_CALL;
+        
         auto can = dynamic_cast<LoopCancellation*>(cancel);
         if(can->Cancelled)
             return S_OK;

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

@@ -247,6 +247,8 @@ public:
     
     virtual HRESULT GetPixelSize(AvnPixelSize* ret)  override
     {
+        START_COM_CALL;
+        
         if(!_surface)
             return E_FAIL;
         *ret = _surface->size;
@@ -255,6 +257,8 @@ public:
     
     virtual HRESULT GetScaling(double* ret)  override
     {
+        START_COM_CALL;
+        
         if(!_surface)
             return E_FAIL;
         *ret = _surface->scale;
@@ -281,6 +285,8 @@ public:
     
     virtual HRESULT BeginDrawing(IAvnGlSurfaceRenderingSession** ret)  override
     {
+        START_COM_CALL;
+        
         ComPtr<IUnknown> releaseContext;
         @synchronized (_target->lock) {
             if(_target->surface == nil)

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

@@ -29,10 +29,12 @@ public:
     IAvnMenu* _mainMenu;
     
     bool _shown;
+    bool _inResize;
     
     WindowBaseImpl(IAvnWindowBaseEvents* events, IAvnGlContext* gl)
     {
         _shown = false;
+        _inResize = false;
         _mainMenu = nullptr;
         BaseEvents = events;
         _glContext = gl;
@@ -54,6 +56,8 @@ public:
     
     virtual HRESULT ObtainNSWindowHandle(void** ret) override
     {
+        START_COM_CALL;
+        
         if (ret == nullptr)
         {
             return E_POINTER;
@@ -66,6 +70,8 @@ public:
     
     virtual HRESULT ObtainNSWindowHandleRetained(void** ret) override
     {
+        START_COM_CALL;
+        
         if (ret == nullptr)
         {
             return E_POINTER;
@@ -78,6 +84,8 @@ public:
     
     virtual HRESULT ObtainNSViewHandle(void** ret) override
     {
+        START_COM_CALL;
+        
         if (ret == nullptr)
         {
             return E_POINTER;
@@ -90,6 +98,8 @@ public:
     
     virtual HRESULT ObtainNSViewHandleRetained(void** ret) override
     {
+        START_COM_CALL;
+        
         if (ret == nullptr)
         {
             return E_POINTER;
@@ -107,23 +117,27 @@ public:
     
     virtual HRESULT Show(bool activate) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             SetPosition(lastPositionSet);
             UpdateStyle();
             
             [Window setContentView: StandardContainer];
+            [Window setTitle:_lastTitle];
             
             if(ShouldTakeFocusOnShow() && activate)
             {
+                [Window orderFront: Window];
                 [Window makeKeyAndOrderFront:Window];
+                [Window makeFirstResponder:View];
                 [NSApp activateIgnoringOtherApps:YES];
             }
             else
             {
                 [Window orderFront: Window];
             }
-            [Window setTitle:_lastTitle];
             
             _shown = true;
             
@@ -138,6 +152,8 @@ public:
     
     virtual HRESULT Hide () override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(Window != nullptr)
@@ -152,6 +168,8 @@ public:
     
     virtual HRESULT Activate () override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(Window != nullptr)
@@ -166,6 +184,8 @@ public:
     
     virtual HRESULT SetTopMost (bool value) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             [Window setLevel: value ? NSFloatingWindowLevel : NSNormalWindowLevel];
@@ -176,11 +196,16 @@ public:
     
     virtual HRESULT Close() override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if (Window != nullptr)
             {
-                [Window close];
+                auto window = Window;
+                Window = nullptr;
+                
+                [window close];
             }
             
             return S_OK;
@@ -189,6 +214,8 @@ public:
     
     virtual HRESULT GetClientSize(AvnSize* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -202,8 +229,25 @@ public:
         }
     }
     
+    virtual HRESULT GetFrameSize(AvnSize* ret) override
+    {
+        @autoreleasepool
+        {
+            if(ret == nullptr)
+                return E_POINTER;
+            
+            auto frame = [Window frame];
+            ret->Width = frame.size.width;
+            ret->Height = frame.size.height;
+            
+            return S_OK;
+        }
+    }
+    
     virtual HRESULT GetScaling (double* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -222,6 +266,8 @@ public:
     
     virtual HRESULT SetMinMaxSize (AvnSize minSize, AvnSize maxSize) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             [Window setMinSize: ToNSSize(minSize)];
@@ -233,6 +279,15 @@ public:
     
     virtual HRESULT Resize(double x, double y) override
     {
+        if(_inResize)
+        {
+            return S_OK;
+        }
+        
+        _inResize = true;
+        
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             auto maxSize = [Window maxSize];
@@ -258,20 +313,28 @@ public:
                 y = maxSize.height;
             }
             
-            if(!_shown)
+            @try
+            {
+                if(!_shown)
+                {
+                    BaseEvents->Resized(AvnSize{x,y});
+                }
+                
+                [Window setContentSize:NSSize{x, y}];
+            }
+            @finally
             {
-                BaseEvents->Resized(AvnSize{x,y});
+                _inResize = false;
             }
             
-            [StandardContainer setFrameSize:NSSize{x,y}];
-            [Window setContentSize:NSSize{x, y}];
-            
             return S_OK;
         }
     }
     
     virtual HRESULT Invalidate (AvnRect rect) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             [View setNeedsDisplayInRect:[View frame]];
@@ -282,6 +345,8 @@ public:
     
     virtual HRESULT SetMainMenu(IAvnMenu* menu) override
     {
+        START_COM_CALL;
+        
         _mainMenu = menu;
         
         auto nativeMenu = dynamic_cast<AvnAppMenu*>(menu);
@@ -300,6 +365,8 @@ public:
     
     virtual HRESULT BeginMoveDrag () override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             auto lastEvent = [View lastMouseDownEvent];
@@ -317,11 +384,15 @@ public:
     
     virtual HRESULT BeginResizeDrag (AvnWindowEdge edge) override
     {
+        START_COM_CALL;
+        
         return S_OK;
     }
     
     virtual HRESULT GetPosition (AvnPoint* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -342,6 +413,8 @@ public:
     
     virtual HRESULT SetPosition (AvnPoint point) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             lastPositionSet = point;
@@ -353,6 +426,8 @@ public:
     
     virtual HRESULT PointToClient (AvnPoint point, AvnPoint* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -371,6 +446,8 @@ public:
     
     virtual HRESULT PointToScreen (AvnPoint point, AvnPoint* ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -388,12 +465,16 @@ public:
     
     virtual HRESULT ThreadSafeSetSwRenderedFrame(AvnFramebuffer* fb, IUnknown* dispose) override
     {
+        START_COM_CALL;
+        
         [View setSwRenderedFrame: fb dispose: dispose];
         return S_OK;
     }
     
     virtual HRESULT SetCursor(IAvnCursor* cursor) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             Cursor* avnCursor = dynamic_cast<Cursor*>(cursor);
@@ -423,6 +504,8 @@ public:
     
     virtual HRESULT CreateGlRenderTarget(IAvnGlSurfaceRenderTarget** ppv) override
     {
+        START_COM_CALL;
+        
         if(View == NULL)
             return E_FAIL;
         *ppv = [renderTarget createSurfaceRenderTarget];
@@ -431,6 +514,8 @@ public:
     
     virtual HRESULT CreateNativeControlHost(IAvnNativeControlHost** retOut) override
     {
+        START_COM_CALL;
+        
         if(View == NULL)
             return E_FAIL;
         *retOut = ::CreateNativeControlHost(View);
@@ -439,6 +524,8 @@ public:
     
     virtual HRESULT SetBlurEnabled (bool enable) override
     {
+        START_COM_CALL;
+        
         [StandardContainer ShowBlur:enable];
         
         return S_OK;
@@ -448,6 +535,8 @@ public:
                                               IAvnClipboard* clipboard, IAvnDndResultCallback* cb,
                                               void* sourceHandle) override
     {
+        START_COM_CALL;
+        
         auto item = TryGetPasteboardItem(clipboard);
         [item setString:@"" forType:GetAvnCustomDataType()];
         if(item == nil)
@@ -513,6 +602,7 @@ private:
     bool _fullScreenActive;
     SystemDecorations _decorations;
     AvnWindowState _lastWindowState;
+    AvnWindowState _actualWindowState;
     bool _inSetWindowState;
     NSRect _preZoomSize;
     bool _transitioningWindowState;
@@ -539,6 +629,7 @@ private:
         _transitioningWindowState = false;
         _inSetWindowState = false;
         _lastWindowState = Normal;
+        _actualWindowState = Normal;
         WindowEvents = events;
         [Window setCanBecomeKeyAndMain];
         [Window disableCursorRects];
@@ -547,6 +638,11 @@ private:
     
     void HideOrShowTrafficLights ()
     {
+        if (Window == nil)
+        {
+            return;
+        }
+        
         for (id subview in Window.contentView.superview.subviews) {
             if ([subview isKindOfClass:NSClassFromString(@"NSTitlebarContainerView")]) {
                 NSView *titlebarView = [subview subviews][0];
@@ -573,8 +669,10 @@ private:
     
     virtual HRESULT Show (bool activate) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
-        {            
+        {
             WindowBaseImpl::Show(activate);
             
             HideOrShowTrafficLights();
@@ -585,6 +683,8 @@ private:
     
     virtual HRESULT SetEnabled (bool enable) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             [Window setEnabled:enable];
@@ -594,6 +694,8 @@ private:
     
     virtual HRESULT SetParent (IAvnWindow* parent) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(parent == nullptr)
@@ -633,7 +735,7 @@ private:
     
     void WindowStateChanged () override
     {
-        if(!_inSetWindowState && !_transitioningWindowState)
+        if(_shown && !_inSetWindowState && !_transitioningWindowState)
         {
             AvnWindowState state;
             GetWindowState(&state);
@@ -670,6 +772,7 @@ private:
                 }
                 
                 _lastWindowState = state;
+                _actualWindowState = state;
                 WindowEvents->WindowStateChanged(state);
             }
         }
@@ -705,6 +808,8 @@ private:
     
     virtual HRESULT SetCanResize(bool value) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             _canResize = value;
@@ -715,6 +820,8 @@ private:
     
     virtual HRESULT SetDecorations(SystemDecorations value) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             auto currentWindowState = _lastWindowState;
@@ -780,6 +887,8 @@ private:
     
     virtual HRESULT SetTitle (char* utf8title) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             _lastTitle = [NSString stringWithUTF8String:(const char*)utf8title];
@@ -791,6 +900,8 @@ private:
     
     virtual HRESULT SetTitleBarColor(AvnColor color) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             float a = (float)color.Alpha / 255.0f;
@@ -820,6 +931,8 @@ private:
     
     virtual HRESULT GetWindowState (AvnWindowState*ret) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if(ret == nullptr)
@@ -853,86 +966,111 @@ private:
     
     virtual HRESULT TakeFocusFromChildren () override
     {
-        if(Window == nil)
-            return S_OK;
-        if([Window isKeyWindow])
-            [Window makeFirstResponder: View];
+        START_COM_CALL;
         
-        return S_OK;
+        @autoreleasepool
+        {
+            if(Window == nil)
+                return S_OK;
+            if([Window isKeyWindow])
+                [Window makeFirstResponder: View];
+            
+            return S_OK;
+        }
     }
     
     virtual HRESULT SetExtendClientArea (bool enable) override
     {
-        _isClientAreaExtended = enable;
+        START_COM_CALL;
         
-        if(enable)
+        @autoreleasepool
         {
-            Window.titleVisibility = NSWindowTitleHidden;
+            _isClientAreaExtended = enable;
             
-            [Window setTitlebarAppearsTransparent:true];
-            
-            auto wantsTitleBar = (_extendClientHints & AvnSystemChrome) || (_extendClientHints & AvnPreferSystemChrome);
-            
-            if (wantsTitleBar)
-            {
-                [StandardContainer ShowTitleBar:true];
-            }
-            else
+            if(enable)
             {
-                [StandardContainer ShowTitleBar:false];
-            }
-            
-            if(_extendClientHints & AvnOSXThickTitleBar)
-            {
-                Window.toolbar = [NSToolbar new];
-                Window.toolbar.showsBaselineSeparator = false;
+                Window.titleVisibility = NSWindowTitleHidden;
+                
+                [Window setTitlebarAppearsTransparent:true];
+                
+                auto wantsTitleBar = (_extendClientHints & AvnSystemChrome) || (_extendClientHints & AvnPreferSystemChrome);
+                
+                if (wantsTitleBar)
+                {
+                    [StandardContainer ShowTitleBar:true];
+                }
+                else
+                {
+                    [StandardContainer ShowTitleBar:false];
+                }
+                
+                if(_extendClientHints & AvnOSXThickTitleBar)
+                {
+                    Window.toolbar = [NSToolbar new];
+                    Window.toolbar.showsBaselineSeparator = false;
+                }
+                else
+                {
+                    Window.toolbar = nullptr;
+                }
             }
             else
             {
+                Window.titleVisibility = NSWindowTitleVisible;
                 Window.toolbar = nullptr;
+                [Window setTitlebarAppearsTransparent:false];
+                View.layer.zPosition = 0;
             }
+            
+            [Window setIsExtended:enable];
+            
+            HideOrShowTrafficLights();
+            
+            UpdateStyle();
+            
+            return S_OK;
         }
-        else
-        {
-            Window.titleVisibility = NSWindowTitleVisible;
-            Window.toolbar = nullptr;
-            [Window setTitlebarAppearsTransparent:false];
-            View.layer.zPosition = 0;
-        }
-        
-        [Window setIsExtended:enable];
-        
-        HideOrShowTrafficLights();
-        
-        UpdateStyle();
-        
-        return S_OK;
     }
     
     virtual HRESULT SetExtendClientAreaHints (AvnExtendClientAreaChromeHints hints) override
     {
-        _extendClientHints = hints;
+        START_COM_CALL;
         
-        SetExtendClientArea(_isClientAreaExtended);
-        return S_OK;
+        @autoreleasepool
+        {
+            _extendClientHints = hints;
+            
+            SetExtendClientArea(_isClientAreaExtended);
+            return S_OK;
+        }
     }
     
     virtual HRESULT GetExtendTitleBarHeight (double*ret) override
     {
-        if(ret == nullptr)
+        START_COM_CALL;
+        
+        @autoreleasepool
         {
-            return E_POINTER;
+            if(ret == nullptr)
+            {
+                return E_POINTER;
+            }
+            
+            *ret = [Window getExtendedTitleBarHeight];
+            
+            return S_OK;
         }
-        
-        *ret = [Window getExtendedTitleBarHeight];
-        
-        return S_OK;
     }
     
     virtual HRESULT SetExtendTitleBarHeight (double value) override
     {
-        [StandardContainer SetTitleBarHeightHint:value];
-        return S_OK;
+        START_COM_CALL;
+        
+        @autoreleasepool
+        {
+            [StandardContainer SetTitleBarHeightHint:value];
+            return S_OK;
+        }
     }
     
     void EnterFullScreenMode ()
@@ -961,16 +1099,23 @@ private:
     
     virtual HRESULT SetWindowState (AvnWindowState state) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
-            if(_lastWindowState == state)
+            if(Window == nullptr)
+            {
+                return  S_OK;
+            }
+            
+            if(_actualWindowState == state)
             {
                 return S_OK;
             }
             
             _inSetWindowState = true;
             
-            auto currentState = _lastWindowState;
+            auto currentState = _actualWindowState;
             _lastWindowState = state;
             
             if(currentState == Normal)
@@ -1049,8 +1194,11 @@ private:
                         }
                         break;
                 }
+                
+                _actualWindowState = _lastWindowState;
             }
             
+            
             _inSetWindowState = false;
             
             return S_OK;
@@ -1144,6 +1292,9 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     [_blurBehind setWantsLayer:true];
     _blurBehind.hidden = true;
     
+    [_blurBehind setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+    [_content setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+    
     [self addSubview:_blurBehind];
     [self addSubview:_content];
     
@@ -1179,9 +1330,6 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     _settingSize = true;
     [super setFrameSize:newSize];
     
-    [_blurBehind setFrameSize:newSize];
-    [_content setFrameSize:newSize];
-    
     auto window = objc_cast<AvnWindow>([self window]);
     
     // TODO get actual titlebar size
@@ -1197,6 +1345,7 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     [_titleBarMaterial setFrame:tbar];
     tbar.size.height = height < 1 ? 0 : 1;
     [_titleBarUnderline setFrame:tbar];
+
     _settingSize = false;
 }
 
@@ -1882,18 +2031,7 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
 
 +(void)closeAll
 {
-    NSArray<NSWindow*>* windows = [NSArray arrayWithArray:[NSApp windows]];
-    auto numWindows = [windows count];
-    
-    for(int i = 0; i < numWindows; i++)
-    {
-        auto window = (AvnWindow*)[windows objectAtIndex:i];
-        
-        if([window parentWindow] == nullptr) // Avalonia will handle the child windows.
-        {
-            [window performClose:nil];
-        }
-    }
+    [[NSApplication sharedApplication] terminate:self];
 }
 
 - (void)performClose:(id)sender
@@ -1906,7 +2044,7 @@ NSArray* AllLoopModes = [NSArray arrayWithObjects: NSDefaultRunLoopMode, NSEvent
     {
         if(![self windowShouldClose:self]) return;
     }
-    
+
     [self close];
 }
 
@@ -2242,11 +2380,12 @@ protected:
     
     virtual HRESULT Resize(double x, double y) override
     {
+        START_COM_CALL;
+        
         @autoreleasepool
         {
             if (Window != nullptr)
             {
-                [StandardContainer setFrameSize:NSSize{x,y}];
                 [Window setContentSize:NSSize{x, y}];
             
                 [Window setFrameTopLeftPoint:ToNSPoint(ConvertPointY(lastPositionSet))];

samples/ControlCatalog/MainWindow.xaml.cs

@@ -17,7 +17,10 @@ namespace ControlCatalog
         public MainWindow()
         {
             this.InitializeComponent();
-            this.AttachDevTools();
+            this.AttachDevTools(new Avalonia.Diagnostics.DevToolsOptions()
+            {
+                StartupScreenIndex = 1,
+            });
             //Renderer.DrawFps = true;
             //Renderer.DrawDirtyRects = Renderer.DrawFps = true;
 

samples/ControlCatalog/Pages/ContextFlyoutPage.axaml

@@ -1,102 +0,0 @@
-<UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-             x:Class="ControlCatalog.Pages.ContextFlyoutPage">
-    <UserControl.Styles>
-        <Style Selector="FlyoutPresenter.NoPadding">
-            <Setter Property="Padding" Value="0" />
-        </Style>
-    </UserControl.Styles>
-    
-    <StackPanel Orientation="Vertical" Spacing="4">
-        <TextBlock Classes="h1">Context Flyout</TextBlock>
-        <TextBlock Classes="h2">A right click Flyout that can be applied to any control.</TextBlock>
-
-        <StackPanel Orientation="Horizontal"
-              Margin="0,16,0,0"
-              HorizontalAlignment="Center"
-              Spacing="16">
-            <Border Background="{DynamicResource SystemAccentColor}"
-                    Margin="16"
-                    Padding="48,48,48,48">
-                <Border.ContextFlyout>
-                    <MenuFlyout>
-                        <MenuItem Header="Standard _Menu Item" InputGesture="Ctrl+A" />
-                        <MenuItem Header="_Disabled Menu Item" IsEnabled="False" InputGesture="Ctrl+D" />
-                        <Separator/>
-                        <MenuItem Header="Menu with _Submenu">
-                            <MenuItem Header="Submenu _1"/>
-                            <MenuItem Header="Submenu _2"/>
-                        </MenuItem>
-                        <MenuItem Header="Menu Item with _Icon" InputGesture="Ctrl+Shift+B">
-                            <MenuItem.Icon>
-                                <Image Source="/Assets/github_icon.png"/>
-                            </MenuItem.Icon>
-                        </MenuItem>
-                        <MenuItem Header="Menu Item with _Checkbox">
-                            <MenuItem.Icon>
-                                <CheckBox BorderThickness="0" IsHitTestVisible="False" IsChecked="True"/>
-                            </MenuItem.Icon>
-                        </MenuItem>
-                    </MenuFlyout>
-                </Border.ContextFlyout>
-                <TextBlock Text="Defined in XAML"/>
-            </Border>
-            <Border Background="{DynamicResource SystemAccentColor}"
-                    Margin="16"
-                    Padding="48,48,48,48">
-                <Border.ContextMenu>
-                    <ContextMenu Items="{Binding MenuItems}">
-                        <ContextMenu.Styles>
-                            <Style Selector="MenuItem">
-                                <Setter Property="Header" Value="{Binding Header}"/>
-                                <Setter Property="Items" Value="{Binding Items}"/>
-                                <Setter Property="Command" Value="{Binding Command}"/>
-                                <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
-                            </Style>
-                        </ContextMenu.Styles>
-                    </ContextMenu>
-                </Border.ContextMenu>
-                <TextBlock Text="Dynamically Generated"/>
-            </Border>
-        </StackPanel>
-
-        <TextBlock Text="Custom ContextFlyout for TextBox" />
-
-        <TextBox Name="TextBox" Width="150" HorizontalAlignment="Center" ContextMenu="{x:Null}">
-            <TextBox.ContextFlyout>
-                <Flyout FlyoutPresenterClasses="NoPadding">
-                    <StackPanel Orientation="Horizontal">
-                        <StackPanel.Styles>
-                            <Style Selector="Button">
-                                <Setter Property="Background" Value="Transparent" />
-                                <Setter Property="Height" Value="40" />
-                                <Setter Property="Width" Value="40" />
-                                <Setter Property="VerticalContentAlignment" Value="Center" />
-                            </Style>
-                            <Style Selector="Button:disabled /template/ ContentPresenter#PART_ContentPresenter">
-                                <Setter Property="Background" Value="Transparent" />
-                                <Setter Property="Opacity" Value="0.5" />
-                            </Style>
-                        </StackPanel.Styles>
-                        <Button Name="CutButton" Command="{Binding $parent[TextBox].Cut}" IsEnabled="{Binding $parent[TextBox].CanCut}">
-                            <PathIcon Width="14" Height="14" Data="M5.22774,2.08072 C5.43359778,1.94704 5.7011484,1.98419259 5.86368634,2.15675215 L5.91939,2.22774 L12.5191,12.3904 C12.956,12.1419 13.4614,12.0000019 14,12.0000019 C15.6569,12.0000019 17,13.3431 17,15.0000019 C17,16.6569 15.6569,18.0000019 14,18.0000019 C12.3431,18.0000019 11,16.6569 11,15.0000019 C11,14.3201402 11.226152,13.693011 11.6073785,13.1899092 L11.7401,13.0269 L10,10.3474 L8.25991,13.0269 C8.72078,13.5543 9,14.2446 9,15.0000019 C9,16.6569 7.65685,18.0000019 6,18.0000019 C4.34315,18.0000019 3,16.6569 3,15.0000019 C3,13.3431 4.34315,12.0000019 6,12.0000019 C6.46163143,12.0000019 6.89890041,12.1042536 7.28955831,12.2905296 L7.4809,12.3904 L9.40382,9.42936 L5.08072,2.77238 C4.93033,2.54079 4.99615,2.23112 5.22774,2.08072 Z M14,13 C12.8954,13 12,13.8954 12,15 C12,16.1046 12.8954,17 14,17 C15.1046,17 16,16.1046 16,15 C16,13.8954 15.1046,13 14,13 Z M6,13 C4.89543,13 4,13.8954 4,15 C4,16.1046 4.89543,17 6,17 C7.10457,17 8,16.1046 8,15 C8,13.8954 7.10457,13 6,13 Z M14.7723,2.08072 C15.0039,2.23112 15.0697,2.54079 14.9193,2.77238 L11.1924,8.51133 L10.5962,7.59329 L14.0806,2.22774 C14.231,1.99615 14.5407,1.93033 14.7723,2.08072 Z" />
-                        </Button>
-                        <Button Name="CopyButton" Content="Copy" Command="{Binding $parent[TextBox].Copy}" IsEnabled="{Binding $parent[TextBox].CanCopy}">
-                            <PathIcon Width="14" Height="14" Data="M5.50280381,4.62704038 L5.5,6.75 L5.5,17.2542087 C5.5,19.0491342 6.95507456,20.5042087 8.75,20.5042087 L17.3662868,20.5044622 C17.057338,21.3782241 16.2239751,22.0042087 15.2444057,22.0042087 L8.75,22.0042087 C6.12664744,22.0042087 4,19.8775613 4,17.2542087 L4,6.75 C4,5.76928848 4.62744523,4.93512464 5.50280381,4.62704038 Z M17.75,2 C18.9926407,2 20,3.00735931 20,4.25 L20,17.25 C20,18.4926407 18.9926407,19.5 17.75,19.5 L8.75,19.5 C7.50735931,19.5 6.5,18.4926407 6.5,17.25 L6.5,4.25 C6.5,3.00735931 7.50735931,2 8.75,2 L17.75,2 Z M17.75,3.5 L8.75,3.5 C8.33578644,3.5 8,3.83578644 8,4.25 L8,17.25 C8,17.6642136 8.33578644,18 8.75,18 L17.75,18 C18.1642136,18 18.5,17.6642136 18.5,17.25 L18.5,4.25 C18.5,3.83578644 18.1642136,3.5 17.75,3.5 Z" />
-                        </Button>
-                        <Button Name="PasteButton" Content="Paste" Command="{Binding $parent[TextBox].Paste}" IsEnabled="{Binding $parent[TextBox].CanPaste}">
-                            <PathIcon Width="14" Height="14" Data="M13.75,2 C14.940864,2 15.9156449,2.92516159 15.9948092,4.09595119 L16,4.25 L16,4.25 C16,4.16530567 15.9953205,4.0817043 15.9862059,3.99944035 L17.75,4 C18.9926407,4 20,5.00735931 20,6.25 L20,19.75 C20,20.9926407 18.9926407,22 17.75,22 L6.25,22 C5.00735931,22 4,20.9926407 4,19.75 L4,6.25 C4,5.00735931 5.00735931,4 6.25,4 L8.01379413,3.99944035 C8.00733496,4.05773764 8.00310309,4.11670658 8.00118552,4.17626017 L8,4.25 C8,3.00735931 9.00735931,2 10.25,2 L13.75,2 Z M13.75,6.5 L10.25,6.5 C9.45594921,6.5 8.75796956,6.08867052 8.357512,5.4674625 L8.37902077,5.50019943 L8.37902077,5.50019943 L6.25,5.5 C5.83578644,5.5 5.5,5.83578644 5.5,6.25 L5.5,19.75 C5.5,20.1642136 5.83578644,20.5 6.25,20.5 L17.75,20.5 C18.1642136,20.5 18.5,20.1642136 18.5,19.75 L18.5,6.25 C18.5,5.83578644 18.1642136,5.5 17.75,5.5 L15.6209792,5.50019943 L15.642488,5.4674625 C15.2420304,6.08867052 14.5440508,6.5 13.75,6.5 Z M13.75,3.5 L10.25,3.5 C9.83578644,3.5 9.5,3.83578644 9.5,4.25 C9.5,4.66421356 9.83578644,5 10.25,5 L13.75,5 C14.1642136,5 14.5,4.66421356 14.5,4.25 C14.5,3.83578644 14.1642136,3.5 13.75,3.5 Z" />
-                        </Button>
-                        <Button Name="ClearButton" Content="Clear" Command="{Binding $parent[TextBox].Clear}">
-                            <PathIcon Width="14" Height="14" Data="M3.52499419,3.71761187 L3.61611652,3.61611652 C4.0717282,3.16050485 4.79154862,3.13013074 5.28238813,3.52499419 L5.38388348,3.61611652 L14,12.233 L22.6161165,3.61611652 C23.1042719,3.12796116 23.8957281,3.12796116 24.3838835,3.61611652 C24.8720388,4.10427189 24.8720388,4.89572811 24.3838835,5.38388348 L15.767,14 L24.3838835,22.6161165 C24.8394952,23.0717282 24.8698693,23.7915486 24.4750058,24.2823881 L24.3838835,24.3838835 C23.9282718,24.8394952 23.2084514,24.8698693 22.7176119,24.4750058 L22.6161165,24.3838835 L14,15.767 L5.38388348,24.3838835 C4.89572811,24.8720388 4.10427189,24.8720388 3.61611652,24.3838835 C3.12796116,23.8957281 3.12796116,23.1042719 3.61611652,22.6161165 L12.233,14 L3.61611652,5.38388348 C3.16050485,4.9282718 3.13013074,4.20845138 3.52499419,3.71761187 L3.61611652,3.61611652 L3.52499419,3.71761187 Z" />
-                        </Button>
-                    </StackPanel>
-                </Flyout>
-            </TextBox.ContextFlyout>
-        </TextBox>
-    
-    </StackPanel>
-</UserControl>

samples/ControlCatalog/Pages/ContextFlyoutPage.axaml.cs

@@ -1,45 +0,0 @@
-using Avalonia;
-using Avalonia.Controls;
-using Avalonia.Markup.Xaml;
-using ControlCatalog.ViewModels;
-using Avalonia.Interactivity;
-namespace ControlCatalog.Pages
-{
-    public class ContextFlyoutPage : UserControl
-    {
-        private TextBox _textBox;
-
-        public ContextFlyoutPage()
-        {
-            InitializeComponent();
-
-            var vm = new ContextFlyoutPageViewModel();
-            vm.View = this;
-            DataContext = vm;
-
-            _textBox = this.FindControl<TextBox>("TextBox");
-
-            var cutButton = this.FindControl<Button>("CutButton");
-            cutButton.Click += CloseFlyout;
-
-            var copyButton = this.FindControl<Button>("CopyButton");
-            copyButton.Click += CloseFlyout;
-
-            var pasteButton = this.FindControl<Button>("PasteButton");
-            pasteButton.Click += CloseFlyout;
-
-            var clearButton = this.FindControl<Button>("ClearButton");
-            clearButton.Click += CloseFlyout;
-        }
-
-        private void CloseFlyout(object sender, RoutedEventArgs e)
-        {
-            _textBox.ContextFlyout.Hide();
-        }
-
-        private void InitializeComponent()
-        {
-            AvaloniaXamlLoader.Load(this);
-        }
-    }
-}

samples/ControlCatalog/Pages/ContextFlyoutPage.xaml

@@ -0,0 +1,157 @@
+<UserControl x:Class="ControlCatalog.Pages.ContextFlyoutPage"
+             xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             d:DesignHeight="450"
+             d:DesignWidth="800"
+             mc:Ignorable="d">
+  <UserControl.Styles>
+    <Style Selector="FlyoutPresenter.NoPadding">
+      <Setter Property="Padding" Value="0" />
+    </Style>
+  </UserControl.Styles>
+
+  <StackPanel Orientation="Vertical" Spacing="4">
+    <StackPanel.Styles>
+      <Style Selector="Border.context-target">
+        <Setter Property="Padding" Value="48,20" />
+        <Setter Property="Margin" Value="8" />
+        <Setter Property="Focusable" Value="True" />
+        <Setter Property="Background" Value="{DynamicResource SystemAccentColor}" />
+      </Style>
+      <Style Selector="Border.context-target > :is(Control)">
+        <Setter Property="VerticalAlignment" Value="Center" />
+      </Style>
+    </StackPanel.Styles>
+    <TextBlock Classes="h1">Context Flyout</TextBlock>
+    <TextBlock Classes="h2">A right click Flyout that can be applied to any control.</TextBlock>
+
+    <UniformGrid HorizontalAlignment="Center" Rows="2">
+      <Border Classes="context-target">
+        <Border.ContextFlyout>
+          <MenuFlyout>
+            <MenuItem Header="Standard _Menu Item" InputGesture="Ctrl+A" />
+            <MenuItem Header="_Disabled Menu Item"
+                      InputGesture="Ctrl+D"
+                      IsEnabled="False" />
+            <Separator />
+            <MenuItem Header="Menu with _Submenu">
+              <MenuItem Header="Submenu _1" />
+              <MenuItem Header="Submenu _2" />
+            </MenuItem>
+            <MenuItem Header="Menu Item with _Icon" InputGesture="Ctrl+Shift+B">
+              <MenuItem.Icon>
+                <Image Source="/Assets/github_icon.png" />
+              </MenuItem.Icon>
+            </MenuItem>
+            <MenuItem Header="Menu Item with _Checkbox">
+              <MenuItem.Icon>
+                <CheckBox BorderThickness="0"
+                          IsChecked="True"
+                          IsHitTestVisible="False" />
+              </MenuItem.Icon>
+            </MenuItem>
+          </MenuFlyout>
+        </Border.ContextFlyout>
+        <TextBlock Text="Defined in XAML" />
+      </Border>
+      <Border Classes="context-target">
+        <Border.Styles>
+          <Style Selector="MenuFlyoutPresenter MenuItem">
+            <Setter Property="Header" Value="{Binding Header}"/>
+            <Setter Property="Items" Value="{Binding Items}"/>
+            <Setter Property="Command" Value="{Binding Command}"/>
+            <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
+          </Style>
+        </Border.Styles>
+        <Border.ContextFlyout>
+          <MenuFlyout Items="{Binding MenuItems}" />
+        </Border.ContextFlyout>
+        <TextBlock Text="Dynamically Generated"/>
+      </Border>
+      <Border x:Name="CustomContextRequestedBorder"
+              Classes="context-target">
+        <Border.ContextFlyout>
+          <Flyout Content="Should never be visible" />
+        </Border.ContextFlyout>
+        <TextBlock Text="Custom ContextRequested handler" TextWrapping="Wrap" />
+      </Border>
+      <Border x:Name="CancellableContextBorder"
+              Classes="context-target">
+        <Border.ContextFlyout>
+          <Flyout>
+            <CheckBox x:Name="CancelCloseCheckBox" Content="Cancel close" />
+          </Flyout>
+        </Border.ContextFlyout>
+        <StackPanel>
+          <TextBlock Text="Cancellable" />
+          <CheckBox x:Name="CancelOpenCheckBox" Content="Cancel open" />
+        </StackPanel>
+      </Border>
+    </UniformGrid>
+
+    <TextBlock Text="Custom ContextFlyout for TextBox" />
+
+    <TextBox Name="TextBox"
+             Width="150"
+             HorizontalAlignment="Center"
+             ContextMenu="{x:Null}">
+      <TextBox.ContextFlyout>
+        <Flyout FlyoutPresenterClasses="NoPadding">
+          <StackPanel>
+          <StackPanel Orientation="Horizontal">
+            <StackPanel.Styles>
+              <Style Selector="Button">
+                <Setter Property="Background" Value="Transparent" />
+                <Setter Property="Height" Value="40" />
+                <Setter Property="Width" Value="40" />
+                <Setter Property="VerticalContentAlignment" Value="Center" />
+              </Style>
+              <Style Selector="Button:disabled /template/ ContentPresenter#PART_ContentPresenter">
+                <Setter Property="Background" Value="Transparent" />
+                <Setter Property="Opacity" Value="0.5" />
+              </Style>
+            </StackPanel.Styles>
+            <Button Name="CutButton"
+                    Command="{Binding $parent[TextBox].Cut}"
+                    IsEnabled="{Binding $parent[TextBox].CanCut}">
+              <PathIcon Width="14"
+                        Height="14"
+                        Data="M5.22774,2.08072 C5.43359778,1.94704 5.7011484,1.98419259 5.86368634,2.15675215 L5.91939,2.22774 L12.5191,12.3904 C12.956,12.1419 13.4614,12.0000019 14,12.0000019 C15.6569,12.0000019 17,13.3431 17,15.0000019 C17,16.6569 15.6569,18.0000019 14,18.0000019 C12.3431,18.0000019 11,16.6569 11,15.0000019 C11,14.3201402 11.226152,13.693011 11.6073785,13.1899092 L11.7401,13.0269 L10,10.3474 L8.25991,13.0269 C8.72078,13.5543 9,14.2446 9,15.0000019 C9,16.6569 7.65685,18.0000019 6,18.0000019 C4.34315,18.0000019 3,16.6569 3,15.0000019 C3,13.3431 4.34315,12.0000019 6,12.0000019 C6.46163143,12.0000019 6.89890041,12.1042536 7.28955831,12.2905296 L7.4809,12.3904 L9.40382,9.42936 L5.08072,2.77238 C4.93033,2.54079 4.99615,2.23112 5.22774,2.08072 Z M14,13 C12.8954,13 12,13.8954 12,15 C12,16.1046 12.8954,17 14,17 C15.1046,17 16,16.1046 16,15 C16,13.8954 15.1046,13 14,13 Z M6,13 C4.89543,13 4,13.8954 4,15 C4,16.1046 4.89543,17 6,17 C7.10457,17 8,16.1046 8,15 C8,13.8954 7.10457,13 6,13 Z M14.7723,2.08072 C15.0039,2.23112 15.0697,2.54079 14.9193,2.77238 L11.1924,8.51133 L10.5962,7.59329 L14.0806,2.22774 C14.231,1.99615 14.5407,1.93033 14.7723,2.08072 Z" />
+            </Button>
+            <Button Name="CopyButton"
+                    Command="{Binding $parent[TextBox].Copy}"
+                    IsEnabled="{Binding $parent[TextBox].CanCopy}">
+              <PathIcon Width="14"
+                        Height="14"
+                        Data="M5.50280381,4.62704038 L5.5,6.75 L5.5,17.2542087 C5.5,19.0491342 6.95507456,20.5042087 8.75,20.5042087 L17.3662868,20.5044622 C17.057338,21.3782241 16.2239751,22.0042087 15.2444057,22.0042087 L8.75,22.0042087 C6.12664744,22.0042087 4,19.8775613 4,17.2542087 L4,6.75 C4,5.76928848 4.62744523,4.93512464 5.50280381,4.62704038 Z M17.75,2 C18.9926407,2 20,3.00735931 20,4.25 L20,17.25 C20,18.4926407 18.9926407,19.5 17.75,19.5 L8.75,19.5 C7.50735931,19.5 6.5,18.4926407 6.5,17.25 L6.5,4.25 C6.5,3.00735931 7.50735931,2 8.75,2 L17.75,2 Z M17.75,3.5 L8.75,3.5 C8.33578644,3.5 8,3.83578644 8,4.25 L8,17.25 C8,17.6642136 8.33578644,18 8.75,18 L17.75,18 C18.1642136,18 18.5,17.6642136 18.5,17.25 L18.5,4.25 C18.5,3.83578644 18.1642136,3.5 17.75,3.5 Z" />
+            </Button>
+            <Button Name="PasteButton"
+                    Command="{Binding $parent[TextBox].Paste}"
+                    IsEnabled="{Binding $parent[TextBox].CanPaste}">
+              <PathIcon Width="14"
+                        Height="14"
+                        Data="M13.75,2 C14.940864,2 15.9156449,2.92516159 15.9948092,4.09595119 L16,4.25 L16,4.25 C16,4.16530567 15.9953205,4.0817043 15.9862059,3.99944035 L17.75,4 C18.9926407,4 20,5.00735931 20,6.25 L20,19.75 C20,20.9926407 18.9926407,22 17.75,22 L6.25,22 C5.00735931,22 4,20.9926407 4,19.75 L4,6.25 C4,5.00735931 5.00735931,4 6.25,4 L8.01379413,3.99944035 C8.00733496,4.05773764 8.00310309,4.11670658 8.00118552,4.17626017 L8,4.25 C8,3.00735931 9.00735931,2 10.25,2 L13.75,2 Z M13.75,6.5 L10.25,6.5 C9.45594921,6.5 8.75796956,6.08867052 8.357512,5.4674625 L8.37902077,5.50019943 L8.37902077,5.50019943 L6.25,5.5 C5.83578644,5.5 5.5,5.83578644 5.5,6.25 L5.5,19.75 C5.5,20.1642136 5.83578644,20.5 6.25,20.5 L17.75,20.5 C18.1642136,20.5 18.5,20.1642136 18.5,19.75 L18.5,6.25 C18.5,5.83578644 18.1642136,5.5 17.75,5.5 L15.6209792,5.50019943 L15.642488,5.4674625 C15.2420304,6.08867052 14.5440508,6.5 13.75,6.5 Z M13.75,3.5 L10.25,3.5 C9.83578644,3.5 9.5,3.83578644 9.5,4.25 C9.5,4.66421356 9.83578644,5 10.25,5 L13.75,5 C14.1642136,5 14.5,4.66421356 14.5,4.25 C14.5,3.83578644 14.1642136,3.5 13.75,3.5 Z" />
+            </Button>
+            <Button Name="ClearButton" Command="{Binding $parent[TextBox].Clear}">
+              <PathIcon Width="14"
+                        Height="14"
+                        Data="M3.52499419,3.71761187 L3.61611652,3.61611652 C4.0717282,3.16050485 4.79154862,3.13013074 5.28238813,3.52499419 L5.38388348,3.61611652 L14,12.233 L22.6161165,3.61611652 C23.1042719,3.12796116 23.8957281,3.12796116 24.3838835,3.61611652 C24.8720388,4.10427189 24.8720388,4.89572811 24.3838835,5.38388348 L15.767,14 L24.3838835,22.6161165 C24.8394952,23.0717282 24.8698693,23.7915486 24.4750058,24.2823881 L24.3838835,24.3838835 C23.9282718,24.8394952 23.2084514,24.8698693 22.7176119,24.4750058 L22.6161165,24.3838835 L14,15.767 L5.38388348,24.3838835 C4.89572811,24.8720388 4.10427189,24.8720388 3.61611652,24.3838835 C3.12796116,23.8957281 3.12796116,23.1042719 3.61611652,22.6161165 L12.233,14 L3.61611652,5.38388348 C3.16050485,4.9282718 3.13013074,4.20845138 3.52499419,3.71761187 L3.61611652,3.61611652 L3.52499419,3.71761187 Z" />
+            </Button>
+          </StackPanel>
+            <Border Classes="context-target"
+                    Padding="4, 20">
+              <Border.ContextFlyout>
+                <Flyout>
+                  <TextBlock>Hello world</TextBlock>
+                </Flyout>
+              </Border.ContextFlyout>
+              <TextBlock>Inner context flyout</TextBlock>
+            </Border>
+          </StackPanel>
+        </Flyout>
+      </TextBox.ContextFlyout>
+    </TextBox>
+  </StackPanel>
+</UserControl>

samples/ControlCatalog/Pages/ContextFlyoutPage.xaml.cs

@@ -0,0 +1,91 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using ControlCatalog.ViewModels;
+using Avalonia.Interactivity;
+using System;
+using System.ComponentModel;
+
+namespace ControlCatalog.Pages
+{
+    public class ContextFlyoutPage : UserControl
+    {
+        private TextBox _textBox;
+
+        public ContextFlyoutPage()
+        {
+            InitializeComponent();
+
+            DataContext = new ContextPageViewModel();
+
+            _textBox = this.FindControl<TextBox>("TextBox");
+
+            var cutButton = this.FindControl<Button>("CutButton");
+            cutButton.Click += CloseFlyout;
+
+            var copyButton = this.FindControl<Button>("CopyButton");
+            copyButton.Click += CloseFlyout;
+
+            var pasteButton = this.FindControl<Button>("PasteButton");
+            pasteButton.Click += CloseFlyout;
+
+            var clearButton = this.FindControl<Button>("ClearButton");
+            clearButton.Click += CloseFlyout;
+
+            var customContextRequestedBorder = this.FindControl<Border>("CustomContextRequestedBorder");
+            customContextRequestedBorder.AddHandler(ContextRequestedEvent, CustomContextRequested, RoutingStrategies.Tunnel);
+
+            var cancellableContextBorder = this.FindControl<Border>("CancellableContextBorder");
+            cancellableContextBorder.ContextFlyout!.Closing += ContextFlyoutPage_Closing;
+            cancellableContextBorder.ContextFlyout!.Opening += ContextFlyoutPage_Opening;
+        }
+
+        private ContextPageViewModel _model;
+        protected override void OnDataContextChanged(EventArgs e)
+        {
+            if (_model != null)
+                _model.View = null;
+            _model = DataContext as ContextPageViewModel;
+            if (_model != null)
+                _model.View = this;
+
+            base.OnDataContextChanged(e);
+        }
+
+        private void ContextFlyoutPage_Closing(object sender, CancelEventArgs e)
+        {
+            var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelCloseCheckBox");
+            e.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+        }
+
+        private void ContextFlyoutPage_Opening(object sender, EventArgs e)
+        {
+            if (e is CancelEventArgs cancelArgs)
+            {
+                var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelOpenCheckBox");
+                cancelArgs.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+            }
+        }
+
+        private void CloseFlyout(object sender, RoutedEventArgs e)
+        {
+            _textBox.ContextFlyout.Hide();
+        }
+
+        public void CustomContextRequested(object sender, ContextRequestedEventArgs e)
+        {
+            var border = (Border)sender;
+            var textBlock = (TextBlock)border.Child;
+
+            textBlock.Text = e.TryGetPosition(border, out var point)
+                ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
+                : "Context was requested without pointer";
+            e.Handled = true;
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

samples/ControlCatalog/Pages/ContextMenuPage.xaml

@@ -1,58 +1,88 @@
-<UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ContextMenuPage">
-    <StackPanel Orientation="Vertical" Spacing="4">
-        <TextBlock Classes="h1">Context Menu</TextBlock>
-        <TextBlock Classes="h2">A right click menu that can be applied to any control.</TextBlock>
+<UserControl x:Class="ControlCatalog.Pages.ContextMenuPage"
+             xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <StackPanel Orientation="Vertical" Spacing="4">
+    <TextBlock Classes="h1">Context Menu</TextBlock>
+    <TextBlock Classes="h2">A right click menu that can be applied to any control.</TextBlock>
 
-        <StackPanel Orientation="Horizontal"
-              Margin="0,16,0,0"
-              HorizontalAlignment="Center"
-              Spacing="16">
-            <Border Background="{DynamicResource SystemAccentColor}"
-                    Margin="16"
-                    Padding="48,48,48,48">
-                <Border.ContextMenu>
-                    <ContextMenu>
-                        <MenuItem Header="Standard _Menu Item" InputGesture="Ctrl+A" />
-                        <MenuItem Header="_Disabled Menu Item" IsEnabled="False" InputGesture="Ctrl+D" />
-                        <Separator/>
-                        <MenuItem Header="Menu with _Submenu">
-                            <MenuItem Header="Submenu _1"/>
-                            <MenuItem Header="Submenu _2"/>
-                        </MenuItem>
-                        <MenuItem Header="Menu Item with _Icon" InputGesture="Ctrl+Shift+B">
-                            <MenuItem.Icon>
-                                <Image Source="/Assets/github_icon.png"/>
-                            </MenuItem.Icon>
-                        </MenuItem>
-                        <MenuItem Header="Menu Item with _Checkbox">
-                            <MenuItem.Icon>
-                                <CheckBox BorderThickness="0" IsHitTestVisible="False" IsChecked="True"/>
-                            </MenuItem.Icon>
-                        </MenuItem>
-                        <MenuItem Header="Menu Item that won't close on click" StaysOpenOnClick="True" />
-                    </ContextMenu>
-                </Border.ContextMenu>
-                <TextBlock Text="Defined in XAML"/>
-            </Border>
-            <Border Background="{DynamicResource SystemAccentColor}"
-                    Margin="16"
-                    Padding="48,48,48,48">
-                <Border.ContextMenu>
-                    <ContextMenu Items="{Binding MenuItems}">
-                        <ContextMenu.Styles>
-                            <Style Selector="MenuItem">
-                                <Setter Property="Header" Value="{Binding Header}"/>
-                                <Setter Property="Items" Value="{Binding Items}"/>
-                                <Setter Property="Command" Value="{Binding Command}"/>
-                                <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
-                            </Style>
-                        </ContextMenu.Styles>
-                    </ContextMenu>
-                </Border.ContextMenu>
-                <TextBlock Text="Dynamically Generated"/>
-            </Border>
+    <UniformGrid HorizontalAlignment="Center" Rows="2">
+      <UniformGrid.Styles>
+        <Style Selector="UniformGrid > Border">
+          <Setter Property="Padding" Value="48,20" />
+          <Setter Property="Margin" Value="8" />
+          <Setter Property="Focusable" Value="True" />
+          <Setter Property="Background" Value="{DynamicResource SystemAccentColor}" />
+        </Style>
+        <Style Selector="UniformGrid > Border > :is(Control)">
+          <Setter Property="VerticalAlignment" Value="Center" />
+        </Style>
+      </UniformGrid.Styles>
+      <Border>
+        <Border.ContextMenu>
+          <ContextMenu>
+            <MenuItem Header="Standard _Menu Item" InputGesture="Ctrl+A" />
+            <MenuItem Header="_Disabled Menu Item"
+                      InputGesture="Ctrl+D"
+                      IsEnabled="False" />
+            <Separator />
+            <MenuItem Header="Menu with _Submenu">
+              <MenuItem Header="Submenu _1" />
+              <MenuItem Header="Submenu _2" />
+            </MenuItem>
+            <MenuItem Header="Menu Item with _Icon" InputGesture="Ctrl+Shift+B">
+              <MenuItem.Icon>
+                <Image Source="/Assets/github_icon.png" />
+              </MenuItem.Icon>
+            </MenuItem>
+            <MenuItem Header="Menu Item with _Checkbox">
+              <MenuItem.Icon>
+                <CheckBox BorderThickness="0"
+                          IsChecked="True"
+                          IsHitTestVisible="False" />
+              </MenuItem.Icon>
+            </MenuItem>
+            <MenuItem Header="Menu Item that won't close on click" StaysOpenOnClick="True" />
+          </ContextMenu>
+        </Border.ContextMenu>
+        <TextBlock Text="Defined in XAML" />
+      </Border>
+      <Border>
+        <Border.Styles>
+          <Style Selector="ContextMenu MenuItem">
+            <Setter Property="Header" Value="{Binding Header}"/>
+            <Setter Property="Items" Value="{Binding Items}"/>
+            <Setter Property="Command" Value="{Binding Command}"/>
+            <Setter Property="CommandParameter" Value="{Binding CommandParameter}"/>
+          </Style>
+        </Border.Styles>
+        <Border.ContextMenu>
+          <ContextMenu Items="{Binding MenuItems}" />
+        </Border.ContextMenu>
+        <TextBlock Text="Dynamically Generated"/>
+      </Border>
+      <Border x:Name="CustomContextRequestedBorder">
+        <Border.ContextMenu>
+          <ContextMenu>
+            <MenuItem Header="Should never be visible" />
+          </ContextMenu>
+        </Border.ContextMenu>
+        <TextBlock Text="Custom ContextRequested handler" TextWrapping="Wrap" />
+      </Border>
+      <Border x:Name="CancellableContextBorder">
+        <Border.ContextMenu>
+          <ContextMenu>
+            <MenuItem>
+              <MenuItem.Header>
+                <CheckBox x:Name="CancelCloseCheckBox" Content="Cancel close" />
+              </MenuItem.Header>
+            </MenuItem>
+          </ContextMenu>
+        </Border.ContextMenu>
+        <StackPanel>
+          <TextBlock Text="Cancellable" />
+          <CheckBox x:Name="CancelOpenCheckBox" Content="Cancel open" />
         </StackPanel>
-    </StackPanel>
+      </Border>
+    </UniformGrid>
+  </StackPanel>
 </UserControl>

samples/ControlCatalog/Pages/ContextMenuPage.xaml.cs

@@ -1,5 +1,8 @@
 using System;
+using System.ComponentModel;
+
 using Avalonia.Controls;
+using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
 using ControlCatalog.ViewModels;
 
@@ -10,21 +13,54 @@ namespace ControlCatalog.Pages
         public ContextMenuPage()
         {
             this.InitializeComponent();
-            DataContext = new ContextMenuPageViewModel();
+            DataContext = new ContextPageViewModel();
+
+            var customContextRequestedBorder = this.FindControl<Border>("CustomContextRequestedBorder");
+            customContextRequestedBorder.AddHandler(ContextRequestedEvent, CustomContextRequested, RoutingStrategies.Tunnel);
+
+            var cancellableContextBorder = this.FindControl<Border>("CancellableContextBorder");
+            cancellableContextBorder.ContextMenu!.ContextMenuClosing += ContextFlyoutPage_Closing;
+            cancellableContextBorder.ContextMenu!.ContextMenuOpening += ContextFlyoutPage_Opening;
         }
 
-        private ContextMenuPageViewModel _model;
+        private ContextPageViewModel _model;
         protected override void OnDataContextChanged(EventArgs e)
         {
             if (_model != null)
                 _model.View = null;
-            _model  = DataContext as ContextMenuPageViewModel;
+            _model  = DataContext as ContextPageViewModel;
             if (_model != null)
                 _model.View = this;
 
             base.OnDataContextChanged(e);
         }
 
+        private void ContextFlyoutPage_Closing(object sender, CancelEventArgs e)
+        {
+            var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelCloseCheckBox");
+            e.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+        }
+
+        private void ContextFlyoutPage_Opening(object sender, EventArgs e)
+        {
+            if (e is CancelEventArgs cancelArgs)
+            {
+                var cancelCloseCheckBox = this.FindControl<CheckBox>("CancelOpenCheckBox");
+                cancelArgs.Cancel = cancelCloseCheckBox.IsChecked ?? false;
+            }
+        }
+
+        public void CustomContextRequested(object sender, ContextRequestedEventArgs e)
+        {
+            var border = (Border)sender;
+            var textBlock = (TextBlock)border.Child;
+
+            textBlock.Text = e.TryGetPosition(border, out var point)
+                ? $"Context was requested with pointer at: {point.X:N0}, {point.Y:N0}"
+                : "Context was requested without pointer";
+            e.Handled = true;
+        }
+
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -23,16 +23,21 @@
     </StackPanel>
     <TabControl Grid.Row="2">
       <TabItem Header="DataGrid">
-        <DataGrid Name="dataGrid1" Margin="12" CanUserResizeColumns="True" CanUserReorderColumns="True" CanUserSortColumns="True" HeadersVisibility="All">
-          <DataGrid.Columns>
-            <DataGridTextColumn Header="Country" Binding="{Binding Name}" Width="6*" />
-            <!-- CompiledBinding example of usage. -->
-            <DataGridTextColumn Header="Region" Binding="{CompiledBinding Region}" Width="4*" x:DataType="local:Country" />
-            <DataGridTextColumn Header="Population" Binding="{Binding Population}" Width="3*" />
-            <DataGridTextColumn Header="Area" Binding="{Binding Area}" Width="3*" />
-            <DataGridTextColumn Header="GDP" Binding="{Binding GDP}" Width="3*" CellStyleClasses="gdp" />
-          </DataGrid.Columns>
-        </DataGrid>
+        <DockPanel>
+          <CheckBox x:Name="ShowGDP"  IsChecked="True"  Content="Toggle GDP Column Visibility"
+                    DockPanel.Dock="Top"/>
+          <DataGrid Name="dataGrid1" Margin="12" CanUserResizeColumns="True" CanUserReorderColumns="True" CanUserSortColumns="True" HeadersVisibility="All">
+            <DataGrid.Columns>
+              <DataGridTextColumn Header="Country" Binding="{Binding Name}" Width="6*" />
+              <!-- CompiledBinding example of usage. -->
+              <DataGridTextColumn Header="Region" Binding="{CompiledBinding Region}" Width="4*" x:DataType="local:Country" />
+              <DataGridTextColumn Header="Population" Binding="{Binding Population}" Width="3*" />
+              <DataGridTextColumn Header="Area" Binding="{Binding Area}" Width="3*" />
+              <DataGridTextColumn Header="GDP" Binding="{Binding GDP}" Width="3*" CellStyleClasses="gdp"
+                                  IsVisible="{Binding #ShowGDP.IsChecked}"/>
+            </DataGrid.Columns>
+          </DataGrid>
+        </DockPanel>
       </TabItem>
       <TabItem Header="Grouping">
         <DataGrid Name="dataGridGrouping" Margin="12">

samples/ControlCatalog/Pages/NumericUpDownPage.xaml

@@ -2,7 +2,8 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:sys="clr-namespace:System;assembly=netstandard"
              x:Class="ControlCatalog.Pages.NumericUpDownPage">
-  <StackPanel Orientation="Vertical" Spacing="4">
+  <StackPanel Orientation="Vertical" Spacing="4"
+              MaxWidth="800">
     <TextBlock Margin="2" Classes="h1">Numeric up-down control</TextBlock>
     <TextBlock Margin="2" Classes="h2" TextWrapping="Wrap">Numeric up-down control provides a TextBox with button spinners that allow incrementing and decrementing numeric values by using the spinner buttons, keyboard up/down arrows, or mouse wheel.</TextBlock>
 
@@ -68,24 +69,36 @@
         <NumericUpDown Grid.Row="3" Grid.Column="1" Value="{Binding #upDown.Value}" VerticalAlignment="Center"
                        Margin="2" HorizontalAlignment="Center"/>
 
+
       </Grid>
     </Grid>
 
-    <StackPanel Margin="2,10,2,2" Orientation="Horizontal" Spacing="10">
-      <TextBlock FontSize="14" FontWeight="Bold" VerticalAlignment="Center">Usage of NumericUpDown:</TextBlock>
-      <NumericUpDown Name="upDown" Minimum="0" Maximum="10" Increment="0.5"
-                     CultureInfo="en-US" VerticalAlignment="Center"
-                     Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}"/>
+    <WrapPanel Margin="2,10,2,2">
+      <StackPanel Orientation="Vertical" Margin="10">
+        <Label Target="upDown" FontSize="14" FontWeight="Bold" VerticalAlignment="Center">Usage of decimal NumericUpDown:</Label>
+        <NumericUpDown Name="upDown" Minimum="0" Maximum="10" Increment="0.5"
+                       CultureInfo="en-US" VerticalAlignment="Center" Value="{Binding DecimalValue}"
+                       Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}"/>
+      </StackPanel>
+
+      <StackPanel Orientation="Vertical" Margin="10">
+        <Label Target="DoubleUpDown" FontSize="14" FontWeight="Bold" VerticalAlignment="Center">Usage of double NumericUpDown:</Label>
+        <NumericUpDown Name="DoubleUpDown" Minimum="0" Maximum="10" Increment="0.5"
+                       CultureInfo="en-US" VerticalAlignment="Center" Value="{Binding DoubleValue}"
+                       Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}"/>
+      </StackPanel>
       
-      <TextBlock FontSize="14" FontWeight="Bold" VerticalAlignment="Center">NumericUpDown with Validation Errors:</TextBlock>
-      <NumericUpDown Minimum="0" Maximum="10" Increment="0.5"
-                     CultureInfo="en-US" VerticalAlignment="Center"
-                     Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}">
-        <DataValidationErrors.Error>
-          <sys:Exception /> 
-        </DataValidationErrors.Error>
-      </NumericUpDown>
-    </StackPanel>
+      <StackPanel Orientation="Vertical" Margin="10">
+        <Label Target="ValidationUpDown" FontSize="14" FontWeight="Bold" VerticalAlignment="Center">NumericUpDown with Validation Errors:</Label>
+        <NumericUpDown x:Name="ValidationUpDown" Minimum="0" Maximum="10" Increment="0.5"
+                       CultureInfo="en-US" VerticalAlignment="Center"
+                       Watermark="Enter text" FormatString="{Binding SelectedFormat.Value}">
+          <DataValidationErrors.Error>
+            <sys:Exception /> 
+          </DataValidationErrors.Error>
+        </NumericUpDown>
+      </StackPanel>
+    </WrapPanel>
 
   </StackPanel>
 </UserControl>

samples/ControlCatalog/Pages/NumericUpDownPage.xaml.cs

@@ -32,11 +32,26 @@ namespace ControlCatalog.Pages
         private FormatObject _selectedFormat;
         private IList<Location> _spinnerLocations;
 
+        private double _doubleValue;
+        private decimal _decimalValue;
+
         public NumbersPageViewModel()
         {
             SelectedFormat = Formats.FirstOrDefault();
         }
 
+        public double DoubleValue
+        {
+            get { return _doubleValue; }
+            set { this.RaiseAndSetIfChanged(ref _doubleValue, value); }
+        }
+
+        public decimal DecimalValue
+        {
+            get { return _decimalValue; }
+            set { this.RaiseAndSetIfChanged(ref _decimalValue, value); }
+        }
+
         public IList<FormatObject> Formats
         {
             get

samples/ControlCatalog/ViewModels/ContextFlyoutPageViewModel.cs

@@ -1,78 +0,0 @@
-using System.Collections.Generic;
-using System.Reactive;
-using System.Threading.Tasks;
-using Avalonia.Controls;
-using Avalonia.VisualTree;
-using MiniMvvm;
-
-namespace ControlCatalog.ViewModels
-{
-    public class ContextFlyoutPageViewModel
-    {
-        public Control View { get; set; }
-        public ContextFlyoutPageViewModel()
-        {
-            OpenCommand = MiniCommand.CreateFromTask(Open);
-            SaveCommand = MiniCommand.Create(Save);
-            OpenRecentCommand = MiniCommand.Create<string>(OpenRecent);
-
-            MenuItems = new[]
-            {
-                new MenuItemViewModel { Header = "_Open...", Command = OpenCommand },
-                new MenuItemViewModel { Header = "Save", Command = SaveCommand },
-                new MenuItemViewModel { Header = "-" },
-                new MenuItemViewModel
-                {
-                    Header = "Recent",
-                    Items = new[]
-                    {
-                        new MenuItemViewModel
-                        {
-                            Header = "File1.txt",
-                            Command = OpenRecentCommand,
-                            CommandParameter = @"c:\foo\File1.txt"
-                        },
-                        new MenuItemViewModel
-                        {
-                            Header = "File2.txt",
-                            Command = OpenRecentCommand,
-                            CommandParameter = @"c:\foo\File2.txt"
-                        },
-                    }
-                },
-            };
-        }
-
-        public IReadOnlyList<MenuItemViewModel> MenuItems { get; set; }
-        public MiniCommand OpenCommand { get; }
-        public MiniCommand SaveCommand { get; }
-        public MiniCommand OpenRecentCommand { get; }
-
-        public async Task Open()
-        {
-            var window = View?.GetVisualRoot() as Window;
-            if (window == null)
-                return;
-            var dialog = new OpenFileDialog();
-            var result = await dialog.ShowAsync(window);
-
-            if (result != null)
-            {
-                foreach (var path in result)
-                {
-                    System.Diagnostics.Debug.WriteLine($"Opened: {path}");
-                }
-            }
-        }
-
-        public void Save()
-        {
-            System.Diagnostics.Debug.WriteLine("Save");
-        }
-
-        public void OpenRecent(string path)
-        {
-            System.Diagnostics.Debug.WriteLine($"Open recent: {path}");
-        }
-    }
-}

samples/ControlCatalog/ViewModels/ContextMenuPageViewModel.cs → samples/ControlCatalog/ViewModels/ContextPageViewModel.cs

@@ -7,10 +7,10 @@ using MiniMvvm;
 
 namespace ControlCatalog.ViewModels
 {
-    public class ContextMenuPageViewModel
+    public class ContextPageViewModel
     {
         public Control View { get; set; }
-        public ContextMenuPageViewModel()
+        public ContextPageViewModel()
         {
             OpenCommand = MiniCommand.CreateFromTask(Open);
             SaveCommand = MiniCommand.Create(Save);

samples/RenderDemo/MainWindow.xaml

@@ -36,6 +36,9 @@
       <TabItem Header="Transitions">
         <pages:TransitionsPage/>
       </TabItem>
+      <TabItem Header="Custom Animator">
+        <pages:CustomAnimatorPage/>
+      </TabItem>
       <TabItem Header="Clipping">
         <pages:ClippingPage/>
       </TabItem>

samples/RenderDemo/Pages/AnimationsPage.xaml

@@ -161,6 +161,151 @@
           </Animation>
         </Style.Animations>
       </Style>
+
+      <Style Selector="Border.Rect7">
+        <Style.Animations>
+          <Animation Duration="0:0:3"
+                     IterationCount="Infinite"
+                     PlaybackDirection="Alternate">
+            <KeyFrame Cue="0%">
+              <Setter Property="Background" Value="Red" />
+            </KeyFrame>
+            <KeyFrame Cue="30%">
+              <Setter Property="Background">
+                <LinearGradientBrush StartPoint="0%,0%" EndPoint="0%,100%">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </LinearGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="60%">
+              <Setter Property="Background" Value="Blue" />
+            </KeyFrame>
+            <KeyFrame Cue="100%">
+              <Setter Property="Background">
+                <LinearGradientBrush StartPoint="0%,0%" EndPoint="0%,100%">
+                  <GradientStop Offset="0" Color="Green"/>
+                  <GradientStop Offset="1" Color="Yellow"/>
+                </LinearGradientBrush>
+              </Setter>
+            </KeyFrame>
+          </Animation>
+        </Style.Animations>
+      </Style>
+
+      <Style Selector="Border.Rect8">
+        <Style.Animations>
+          <Animation Duration="0:0:3"
+                     IterationCount="Infinite"
+                     PlaybackDirection="Alternate">
+            <KeyFrame Cue="0%">
+              <Setter Property="Background">
+                <LinearGradientBrush StartPoint="0%,0%" EndPoint="0%,100%">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </LinearGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="50%">
+              <Setter Property="Background">
+                <LinearGradientBrush StartPoint="100%,0%" EndPoint="0%,100%">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="0.25" Color="Blue"/>
+                  <GradientStop Offset="0.5" Color="Blue"/>
+                  <GradientStop Offset="0.75" Color="Green"/>
+                  <GradientStop Offset="1" Color="Yellow"/>
+                </LinearGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="100%">
+              <Setter Property="Background">
+                <LinearGradientBrush StartPoint="0%,0%" EndPoint="0%,100%">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </LinearGradientBrush>
+              </Setter>
+            </KeyFrame>
+          </Animation>
+        </Style.Animations>
+      </Style>
+
+      <Style Selector="Border.Rect9">
+        <Style.Animations>
+          <Animation Duration="0:0:3"
+                     IterationCount="Infinite"
+                     PlaybackDirection="Alternate">
+            <KeyFrame Cue="0%">
+              <Setter Property="Background">
+                <ConicGradientBrush Center="50%,50%" Angle="0">
+                  <GradientStop Offset="0" Color="Blue"/>
+                  <GradientStop Offset="0.5" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </ConicGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="100%">
+              <Setter Property="Background">
+                <ConicGradientBrush Center="50%,70%" Angle="90">
+                  <GradientStop Offset="0" Color="Green"/>
+                  <GradientStop Offset="0.25" Color="Yellow"/>
+                  <GradientStop Offset="0.5" Color="Red"/>
+                  <GradientStop Offset="0.75" Color="Blue"/>
+                  <GradientStop Offset="1" Color="Green"/>
+                </ConicGradientBrush>
+              </Setter>
+            </KeyFrame>
+          </Animation>
+        </Style.Animations>
+      </Style>
+
+      <Style Selector="Border.Rect10">
+        <Style.Animations>
+          <Animation Duration="0:0:3"
+                     IterationCount="Infinite"
+                     PlaybackDirection="Normal">
+            <KeyFrame Cue="0%">
+              <Setter Property="Background">
+                <RadialGradientBrush Center="0%,100%" Radius="0.8">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </RadialGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="25%">
+              <Setter Property="Background">
+                <RadialGradientBrush Center="0%,0%" Radius="1">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </RadialGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="50%">
+              <Setter Property="Background">
+                <RadialGradientBrush Center="100%,0%" Radius="0.8">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </RadialGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="75%">
+              <Setter Property="Background">
+                <RadialGradientBrush Center="100%,100%" Radius="1">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </RadialGradientBrush>
+              </Setter>
+            </KeyFrame>
+            <KeyFrame Cue="100%">
+              <Setter Property="Background">
+                <RadialGradientBrush Center="0%,100%" Radius="0.8">
+                  <GradientStop Offset="0" Color="Red"/>
+                  <GradientStop Offset="1" Color="Blue"/>
+                </RadialGradientBrush>
+              </Setter>
+            </KeyFrame>
+          </Animation>
+        </Style.Animations>
+      </Style>
     </Styles>
   </UserControl.Styles>
   <Grid>
@@ -181,6 +326,10 @@
         <Border Classes="Test Rect6" Background="Red"/>
         <Border Classes="Test Shadow" CornerRadius="10" Child="{x:Null}" />
         <Border Classes="Test Shadow" CornerRadius="0 30 60 0" Child="{x:Null}" />
+        <Border Classes="Test Rect7" Child="{x:Null}" />
+        <Border Classes="Test Rect8" Child="{x:Null}" />
+        <Border Classes="Test Rect9" Child="{x:Null}" />
+        <Border Classes="Test Rect10" Child="{x:Null}" />
       </WrapPanel>
     </StackPanel>
   </Grid>

samples/RenderDemo/Pages/CustomAnimatorPage.xaml

@@ -0,0 +1,25 @@
+<UserControl 
+  xmlns="https://github.com/avaloniaui" 
+  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
+  xmlns:pages="clr-namespace:RenderDemo.Pages"
+  x:Class="RenderDemo.Pages.CustomAnimatorPage"
+  MaxWidth="600">
+  <Grid>
+    <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center">
+      <TextBlock.Styles>
+        <Style Selector="TextBlock">
+          <Style.Animations>
+            <Animation Duration="0:0:1" IterationCount="Infinite">
+              <KeyFrame Cue="0%">
+                <Setter Property="Text" Value="" Animation.Animator="{x:Type pages:CustomStringAnimator}"/>
+              </KeyFrame>
+              <KeyFrame Cue="100%">
+                <Setter Property="Text" Value="0123456789" Animation.Animator="{x:Type pages:CustomStringAnimator}"/>
+              </KeyFrame>
+            </Animation>
+          </Style.Animations>
+        </Style>
+      </TextBlock.Styles>
+    </TextBlock>
+  </Grid>
+</UserControl>

samples/RenderDemo/Pages/CustomAnimatorPage.xaml.cs

@@ -0,0 +1,27 @@
+using System.Reactive.Linq;
+using Avalonia;
+using Avalonia.Animation;
+using Avalonia.Controls;
+using Avalonia.Controls.Shapes;
+using Avalonia.Data;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media;
+using RenderDemo.ViewModels;
+
+namespace RenderDemo.Pages
+{
+    public class CustomAnimatorPage : UserControl
+    {
+        public CustomAnimatorPage()
+        {
+            InitializeComponent();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

samples/RenderDemo/Pages/CustomStringAnimator.cs

@@ -0,0 +1,16 @@
+using Avalonia.Animation.Animators;
+
+namespace RenderDemo.Pages
+{
+    public class CustomStringAnimator : Animator<string>
+    {
+        public override string Interpolate(double progress, string oldValue, string newValue)
+        {
+            if (newValue.Length == 0) return "";
+            var step = 1.0 / newValue.Length;
+            var length = (int)(progress / step);
+            var result = newValue.Substring(0, length + 1);
+            return result;
+        }
+    }
+}

samples/RenderDemo/Pages/TransitionsPage.xaml

@@ -141,6 +141,106 @@
       <Style Selector="Border.Shadow:pointerover">
         <Setter Property="BoxShadow" Value="inset 30 30 20 30 Green, 20 40 20 10 Red"/>
       </Style>
+
+      <Style Selector="Border.Rect10">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" Value="Red" />
+      </Style>
+
+      <Style Selector="Border.Rect10:pointerover">
+        <Setter Property="Background" Value="Orange" />
+      </Style>
+
+      <Style Selector="Border.Rect11">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" Value="Red" />
+      </Style>
+
+      <Style Selector="Border.Rect11:pointerover">
+        <Setter Property="Background" >
+          <LinearGradientBrush StartPoint="0%,0%" EndPoint="100%,100%">
+            <GradientStop Offset="0" Color="Red"/>
+            <GradientStop Offset="1" Color="Blue"/>
+          </LinearGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect12">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" >
+          <LinearGradientBrush StartPoint="0%,0%" EndPoint="100%,100%">
+            <GradientStop Offset="0" Color="Red"/>
+            <GradientStop Offset="1" Color="Blue"/>
+          </LinearGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect12:pointerover">
+        <Setter Property="Background" >
+          <LinearGradientBrush StartPoint="100%,0%" EndPoint="0%,100%">
+            <GradientStop Offset="0" Color="Green"/>
+            <GradientStop Offset="1" Color="Yellow"/>
+          </LinearGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect13">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" >
+          <ConicGradientBrush Center="50%,50%" Angle="0">
+            <GradientStop Offset="0" Color="Red"/>
+            <GradientStop Offset="1" Color="Blue"/>
+          </ConicGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect13:pointerover">
+        <Setter Property="Background" >
+          <ConicGradientBrush Center="70%,70%" Angle="90">
+            <GradientStop Offset="0" Color="Green"/>
+            <GradientStop Offset="1" Color="Yellow"/>
+          </ConicGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect14">
+        <Setter Property="Transitions">
+          <Transitions>
+            <BrushTransition Property="Background" Duration="0:0:0.5" />
+          </Transitions>
+        </Setter>
+        <Setter Property="Background" >
+          <RadialGradientBrush Center="50%,50%" Radius="0.5">
+            <GradientStop Offset="0" Color="Red"/>
+            <GradientStop Offset="1" Color="Blue"/>
+          </RadialGradientBrush>
+        </Setter>
+      </Style>
+
+      <Style Selector="Border.Rect14:pointerover">
+        <Setter Property="Background" >
+          <RadialGradientBrush Center="30%,30%" Radius="0.2">
+            <GradientStop Offset="0" Color="Green"/>
+            <GradientStop Offset="1" Color="Yellow"/>
+          </RadialGradientBrush>
+        </Setter>
+      </Style>
     </Styles>
   </UserControl.Styles>
 
@@ -166,6 +266,18 @@
 
         <Border Classes="Test Shadow" CornerRadius="10" Child="{x:Null}" />
         <Border Classes="Test Shadow" CornerRadius="0 30 60 0" Child="{x:Null}" />
+
+        <Border Classes="Test Rect10" />
+        <Border Classes="Test Rect11" />
+
+        <Border Classes="Test Rect12" Child="{x:Null}"/>
+        <Border Classes="Test Rect13" Child="{x:Null}"/>
+        <Border Classes="Test Rect14" Child="{x:Null}"/>
+        
+        <Border Classes="Test Rect14" />
+        <Border Classes="Test Rect14" />
+        <Border Classes="Test Rect14" />
+        <Border Classes="Test Rect14" />
       </WrapPanel>
     </StackPanel>
   </Grid>

samples/Sandbox/Program.cs

@@ -4,12 +4,12 @@ namespace Sandbox
 {
     public class Program
     {
-        static void Main(string[] args)
-        {
+        static void Main(string[] args) => BuildAvaloniaApp()
+            .StartWithClassicDesktopLifetime(args);
+
+        public static AppBuilder BuildAvaloniaApp() =>
             AppBuilder.Configure<App>()
                 .UsePlatformDetect()
-                .LogToTrace()
-                .StartWithClassicDesktopLifetime(args);
-        }
+                .LogToTrace();
     }
 }

src/Android/Avalonia.Android/Platform/SkiaPlatform/TopLevelImpl.cs

@@ -55,6 +55,8 @@ namespace Avalonia.Android.Platform.SkiaPlatform
 
         public virtual Size ClientSize => Size.ToSize(RenderScaling);
 
+        public Size? FrameSize => null;
+
         public IMouseDevice MouseDevice { get; } = new MouseDevice();
 
         public Action Closed { get; set; }

src/Avalonia.Animation/Animation.cs

@@ -3,10 +3,11 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Disposables;
 using System.Reactive.Linq;
+using System.Threading;
 using System.Threading.Tasks;
+
 using Avalonia.Animation.Animators;
 using Avalonia.Animation.Easings;
-using Avalonia.Collections;
 using Avalonia.Data;
 using Avalonia.Metadata;
 
@@ -194,6 +195,33 @@ namespace Avalonia.Animation
         [Content]
         public KeyFrames Children { get; } = new KeyFrames();
 
+        // Store values for the Animator attached properties for IAnimationSetter objects.
+        private static readonly Dictionary<IAnimationSetter, Type> s_animators = new Dictionary<IAnimationSetter, Type>();
+
+        /// <summary>
+        /// Gets the value of the Animator attached property for a setter.
+        /// </summary>
+        /// <param name="setter">The animation setter.</param>
+        /// <returns>The property animator type.</returns>
+        public static Type GetAnimator(IAnimationSetter setter)
+        {
+            if (s_animators.TryGetValue(setter, out var type))
+            {
+                return type;
+            }
+            return null;
+        }
+
+        /// <summary>
+        /// Sets the value of the Animator attached property for a setter.
+        /// </summary>
+        /// <param name="setter">The animation setter.</param>
+        /// <param name="value">The property animator value.</param>
+        public static void SetAnimator(IAnimationSetter setter, Type value)
+        {
+            s_animators[setter] = value;
+        }
+
         private readonly static List<(Func<AvaloniaProperty, bool> Condition, Type Animator)> Animators = new List<(Func<AvaloniaProperty, bool>, Type)>
         {
             ( prop => typeof(bool).IsAssignableFrom(prop.PropertyType), typeof(BoolAnimator) ),
@@ -248,7 +276,7 @@ namespace Avalonia.Animation
             {
                 foreach (var setter in keyframe.Setters)
                 {
-                    var handler = GetAnimatorType(setter.Property);
+                    var handler = Animation.GetAnimator(setter) ?? GetAnimatorType(setter.Property);
 
                     if (handler == null)
                     {
@@ -292,7 +320,7 @@ namespace Avalonia.Animation
             return (newAnimatorInstances, subscriptions);
         }
 
-        /// <inheritdocs/>
+        /// <inheritdoc/>
         public IDisposable Apply(Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
         {
             var (animators, subscriptions) = InterpretKeyframes(control);
@@ -317,25 +345,40 @@ namespace Avalonia.Animation
 
                 if (onComplete != null)
                 {
-                    Task.WhenAll(completionTasks).ContinueWith(_ => onComplete());
+                    Task.WhenAll(completionTasks).ContinueWith(
+                        (_, state) => ((Action)state).Invoke(),
+                        onComplete);
                 }
             }
             return new CompositeDisposable(subscriptions);
         }
 
-        /// <inheritdocs/>
-        public Task RunAsync(Animatable control, IClock clock = null)
+        /// <inheritdoc/>
+        public Task RunAsync(Animatable control, IClock clock = null, CancellationToken cancellationToken = default)
         {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return Task.CompletedTask;
+            }
+
             var run = new TaskCompletionSource<object>();
 
             if (this.IterationCount == IterationCount.Infinite)
                 run.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
 
-            IDisposable subscriptions = null;
+            IDisposable subscriptions = null, cancellation = null;
             subscriptions = this.Apply(control, clock, Observable.Return(true), () =>
             {
-                run.SetResult(null);
+                run.TrySetResult(null);
+                subscriptions?.Dispose();
+                cancellation?.Dispose();
+            });
+
+            cancellation = cancellationToken.Register(() =>
+            {
+                run.TrySetResult(null);
                 subscriptions?.Dispose();
+                cancellation?.Dispose();
             });
 
             return run.Task;

src/Avalonia.Animation/AnimationInstance`1.cs

@@ -5,6 +5,7 @@ using Avalonia.Animation.Animators;
 using Avalonia.Animation.Utils;
 using Avalonia.Data;
 using Avalonia.Reactive;
+using JetBrains.Annotations;
 
 namespace Avalonia.Animation
 {
@@ -36,6 +37,7 @@ namespace Avalonia.Animation
         private IDisposable _timerSub;
         private readonly IClock _baseClock;
         private IClock _clock;
+        private EventHandler<AvaloniaPropertyChangedEventArgs> _propertyChangedDelegate;
 
         public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, IClock baseClock, Action OnComplete, Func<double, T, T> Interpolator)
         {
@@ -45,8 +47,6 @@ namespace Avalonia.Animation
             _onCompleteAction = OnComplete;
             _interpolator = Interpolator;
             _baseClock = baseClock;
-            _neutralValue = (T)_targetControl.GetValue(_animator.Property);
-
             FetchProperties();
         }
 
@@ -80,6 +80,7 @@ namespace Avalonia.Animation
             // Animation may have been stopped before it has finished.
             ApplyFinalFill();
 
+            _targetControl.PropertyChanged -= _propertyChangedDelegate;
             _timerSub?.Dispose();
             _clock.PlayState = PlayState.Stop;
         }
@@ -88,6 +89,9 @@ namespace Avalonia.Animation
         {
             _clock = new Clock(_baseClock);
             _timerSub = _clock.Subscribe(Step);
+            _propertyChangedDelegate ??= ControlPropertyChanged;
+            _targetControl.PropertyChanged += _propertyChangedDelegate;
+            UpdateNeutralValue();
         }
 
         public void Step(TimeSpan frameTick)
@@ -216,5 +220,22 @@ namespace Avalonia.Animation
                 }
             }
         }
+
+        private void UpdateNeutralValue()
+        {
+            var property = _animator.Property;
+            var baseValue = _targetControl.GetBaseValue(property, BindingPriority.LocalValue);
+
+            _neutralValue = baseValue != AvaloniaProperty.UnsetValue ?
+                (T)baseValue : (T)_targetControl.GetValue(property);
+        }
+
+        private void ControlPropertyChanged(object sender, AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Property == _animator.Property && e.Priority > BindingPriority.Animation)
+            {
+                UpdateNeutralValue();
+            }
+        }
     }
 }

src/Avalonia.Animation/ApiCompatBaseline.txt

@@ -0,0 +1,6 @@
+Compat issues with assembly Avalonia.Animation:
+MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.Animation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' is present in the contract but not in the implementation.
+MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock, System.Threading.CancellationToken)' is present in the implementation but not in the contract.
+Total Issues: 4

src/Avalonia.Animation/IAnimation.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace Avalonia.Animation
@@ -16,6 +17,6 @@ namespace Avalonia.Animation
         /// <summary>
         /// Run the animation on the specified control.
         /// </summary>
-        Task RunAsync(Animatable control, IClock clock);
+        Task RunAsync(Animatable control, IClock clock, CancellationToken cancellationToken = default);
     }
 }

src/Avalonia.Base/AvaloniaObjectExtensions.cs

@@ -585,6 +585,30 @@ namespace Avalonia
             });
         }
 
+        /// <summary>
+        /// Subscribes to a property changed notifications for changes that originate from a
+        /// <typeparamref name="TTarget"/>.
+        /// </summary>
+        /// <typeparam name="TTarget">The type of the property change sender.</typeparam>
+        /// /// <typeparam name="TValue">The type of the property..</typeparam>
+        /// <param name="observable">The property changed observable.</param>
+        /// <param name="action">
+        /// The method to call. The parameters are the sender and the event args.
+        /// </param>
+        /// <returns>A disposable that can be used to terminate the subscription.</returns>
+        public static IDisposable AddClassHandler<TTarget, TValue>(
+            this IObservable<AvaloniaPropertyChangedEventArgs<TValue>> observable,
+            Action<TTarget, AvaloniaPropertyChangedEventArgs<TValue>> action) where TTarget : AvaloniaObject
+        {
+            return observable.Subscribe(e =>
+            {
+                if (e.Sender is TTarget target)
+                {
+                    action(target, e);
+                }
+            });
+        }
+
         /// <summary>
         /// Subscribes to a property changed notifications for changes that originate from a
         /// <typeparamref name="TTarget"/>.

src/Avalonia.Base/Collections/AvaloniaList.cs

@@ -454,6 +454,28 @@ namespace Avalonia.Collections
             }
         }
 
+        /// <summary>
+        /// Ensures that the capacity of the list is at least <see cref="capacity"/>.
+        /// </summary>
+        /// <param name="capacity">The capacity.</param>
+        public void EnsureCapacity(int capacity)
+        {
+            // Adapted from List<T> implementation.
+            var currentCapacity = _inner.Capacity;
+
+            if (currentCapacity < capacity)
+            {
+                var newCapacity = currentCapacity == 0 ? 4 : currentCapacity * 2;
+
+                if (newCapacity < capacity)
+                {
+                    newCapacity = capacity;
+                }
+
+                _inner.Capacity = newCapacity;
+            }
+        }
+
         /// <summary>
         /// Removes an item from the collection.
         /// </summary>
@@ -633,24 +655,6 @@ namespace Avalonia.Collections
         /// <inheritdoc/>
         Delegate[] INotifyCollectionChangedDebug.GetCollectionChangedSubscribers() => _collectionChanged?.GetInvocationList();
 
-        private void EnsureCapacity(int capacity)
-        {
-            // Adapted from List<T> implementation.
-            var currentCapacity = _inner.Capacity;
-
-            if (currentCapacity < capacity)
-            {
-                var newCapacity = currentCapacity == 0 ? 4 : currentCapacity * 2;
-
-                if (newCapacity < capacity)
-                {
-                    newCapacity = capacity;
-                }
-
-                _inner.Capacity = newCapacity;
-            }
-        }
-
         /// <summary>
         /// Raises the <see cref="CollectionChanged"/> event with an add action.
         /// </summary>

src/Avalonia.Base/Metadata/NullableAttributes.cs

@@ -1,6 +1,5 @@
 #pragma warning disable MA0048 // File name must match type name
 #define INTERNAL_NULLABLE_ATTRIBUTES
-#if NETSTANDARD2_0 ||  NETCOREAPP2_0 ||  NETCOREAPP2_1 ||  NETCOREAPP2_2 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
 
 // https://github.com/dotnet/corefx/blob/48363ac826ccf66fbe31a5dcb1dc2aab9a7dd768/src/Common/src/CoreLib/System/Diagnostics/CodeAnalysis/NullableAttributes.cs
 
@@ -10,6 +9,7 @@
 
 namespace System.Diagnostics.CodeAnalysis
 {
+#if NETSTANDARD2_0 || NETCOREAPP2_0 || NETCOREAPP2_1 || NETCOREAPP2_2 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
     /// <summary>Specifies that null is allowed as an input even if the corresponding type disallows it.</summary>
     [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
 #if INTERNAL_NULLABLE_ATTRIBUTES
@@ -136,5 +136,82 @@ namespace System.Diagnostics.CodeAnalysis
         /// <summary>Gets the condition parameter value.</summary>
         public bool ParameterValue { get; }
     }
-}
+#endif // NETSTANDARD2_0 attributes
+
+#if NETSTANDARD2_1 || NETSTANDARD2_0 || NETCOREAPP2_0 || NETCOREAPP2_1 || NETCOREAPP2_2 || NETCOREAPP3_1 || NET45 || NET451 || NET452 || NET6 || NET461 || NET462 || NET47 || NET471 || NET472 || NET48
+    /// <summary>
+    /// Specifies that the method or property will ensure that the listed field and property members have
+    /// not-<see langword="null"/> values.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
 #endif
+    sealed class MemberNotNullAttribute : Attribute
+    {
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+
+        /// <summary>Initializes the attribute with a field or property member.</summary>
+        /// <param name="member">The field or property member that is promised to be not-null.</param>
+        public MemberNotNullAttribute(string member)
+        {
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the list of field and property members.</summary>
+        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
+        public MemberNotNullAttribute(params string[] members)
+        {
+            Members = members;
+        }
+    }
+
+    /// <summary>
+    /// Specifies that the method or property will ensure that the listed field and property members have
+    /// non-<see langword="null"/> values when returning with the specified return value condition.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
+#endif
+    sealed class MemberNotNullWhenAttribute : Attribute
+    {
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+
+        /// <summary>Initializes the attribute with the specified return value condition and a field or property member.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value,
+        /// the associated parameter will not be <see langword="null"/>.
+        /// </param>
+        /// <param name="member">The field or property member that is promised to be not-<see langword="null"/>.</param>
+        public MemberNotNullWhenAttribute(bool returnValue, string member)
+        {
+            ReturnValue = returnValue;
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the specified return value condition and list of field and property members.
+        /// </summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value,
+        /// the associated parameter will not be <see langword="null"/>.
+        /// </param>
+        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
+        public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
+        {
+            ReturnValue = returnValue;
+            Members = members;
+        }
+    }
+#endif // NETSTANDARD2_1 attributes
+}
+

src/Avalonia.Base/Utilities/MathUtilities.cs

@@ -224,6 +224,34 @@ namespace Avalonia.Utilities
             }
         }
 
+        /// <summary>
+        /// Clamps a value between a minimum and maximum value.
+        /// </summary>
+        /// <param name="val">The value.</param>
+        /// <param name="min">The minimum value.</param>
+        /// <param name="max">The maximum value.</param>
+        /// <returns>The clamped value.</returns>
+        public static decimal Clamp(decimal val, decimal min, decimal max)
+        {
+            if (min > max)
+            {
+                ThrowCannotBeGreaterThanException(min, max);
+            }
+
+            if (val < min)
+            {
+                return min;
+            }
+            else if (val > max)
+            {
+                return max;
+            }
+            else
+            {
+                return val;
+            }
+        }
+
         /// <summary>
         /// Clamps a value between a minimum and maximum value.
         /// </summary>
@@ -281,8 +309,8 @@ namespace Avalonia.Utilities
         {
             return angle * 2 * Math.PI;
         }
-        
-        private static void ThrowCannotBeGreaterThanException(double min, double max)
+
+        private static void ThrowCannotBeGreaterThanException<T>(T min, T max)
         {
             throw new ArgumentException($"{min} cannot be greater than {max}.");
         }

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -75,7 +75,6 @@ namespace Avalonia.Controls
         private const double DATAGRID_defaultMinColumnWidth = 20;
         private const double DATAGRID_defaultMaxColumnWidth = double.PositiveInfinity;
 
-        private List<Exception> _validationErrors;
         private List<Exception> _bindingValidationErrors;
         private IDisposable _validationSubscription;
 
@@ -102,7 +101,6 @@ namespace Avalonia.Controls
         private bool _areHandlersSuspended;
         private bool _autoSizingColumns;
         private IndexToValueTable<bool> _collapsedSlotsTable;
-        private DataGridCellCoordinates _currentCellCoordinates;
         private Control _clickedElement;
 
         // used to store the current column during a Reset
@@ -141,7 +139,6 @@ namespace Avalonia.Controls
         private DataGridSelectedItemsCollection _selectedItems;
         private bool _temporarilyResetCurrentCell;
         private object _uneditedValue; // Represents the original current cell value at the time it enters editing mode.
-        private ICellEditBinding _currentCellEditBinding;
 
         // An approximation of the sum of the heights in pixels of the scrolling rows preceding
         // the first displayed scrolling row.  Since the scrolled off rows are discarded, the grid

src/Avalonia.Controls.DataGrid/DataGridColumn.cs

@@ -27,7 +27,6 @@ namespace Avalonia.Controls
         private double? _minWidth;
         private bool _settingWidthInternally;
         private int _displayIndexWithFiller;
-        private bool _isVisible;
         private object _header;
         private DataGridColumnHeader _headerCell;
         private IControl _editingElement;
@@ -40,7 +39,6 @@ namespace Avalonia.Controls
         /// </summary>
         protected internal DataGridColumn()
         {
-            _isVisible = true;
             _displayIndexWithFiller = -1;
             IsInitialDesiredWidthDetermined = false;
             InheritsWidth = true;
@@ -174,32 +172,42 @@ namespace Avalonia.Controls
             get => _editBinding;
         }
 
+
+        /// <summary>
+        /// Defines the <see cref="IsVisible"/> property.
+        /// </summary>
+        public static StyledProperty<bool> IsVisibleProperty =
+             Control.IsVisibleProperty.AddOwner<DataGridColumn>();
+
         /// <summary>
         /// Determines whether or not this column is visible.
         /// </summary>
         public bool IsVisible
         {
-            get
-            {
-                return _isVisible;
-            }
-            set
-            {
-                if (value != IsVisible)
-                {
-                    OwningGrid?.OnColumnVisibleStateChanging(this);
-                    _isVisible = value;
+            get => GetValue(IsVisibleProperty);
+            set => SetValue(IsVisibleProperty, value);
+        }
 
-                    if (_headerCell != null)
-                    {
-                        _headerCell.IsVisible = value;
-                    }
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
+        {
+            base.OnPropertyChanged(change);
 
-                    OwningGrid?.OnColumnVisibleStateChanged(this);
+            if (change.Property == IsVisibleProperty)
+            {
+                OwningGrid?.OnColumnVisibleStateChanging(this);
+                var isVisible = (change as AvaloniaPropertyChangedEventArgs<bool>).NewValue.Value;
+
+                if (_headerCell != null)
+                {
+                    _headerCell.IsVisible = isVisible;
                 }
+
+                OwningGrid?.OnColumnVisibleStateChanged(this);
+                NotifyPropertyChanged(change.Property.Name);
             }
         }
 
+
         /// <summary>
         /// Actual visible width after Width, MinWidth, and MaxWidth setting at the Column level and DataGrid level
         /// have been taken into account

src/Avalonia.Controls.DataGrid/DataGridRows.cs

@@ -425,7 +425,7 @@ namespace Avalonia.Controls
                 UpdateDisplayedRows(DisplayData.FirstScrollingSlot, CellsHeight);
             }
 
-            if (DisplayData.FirstScrollingSlot < slot && DisplayData.LastScrollingSlot > slot)
+            if (DisplayData.FirstScrollingSlot < slot && (DisplayData.LastScrollingSlot > slot || DisplayData.LastScrollingSlot == -1))
             {
                 // The row is already displayed in its entirety
                 return true;

src/Avalonia.Controls.DataGrid/Themes/Fluent.xaml

@@ -6,8 +6,8 @@
     <x:Double x:Key="ListAccentLowOpacity">0.6</x:Double>
     <x:Double x:Key="ListAccentMediumOpacity">0.8</x:Double>
 
-    <StreamGeometry x:Key="DataGridSortIconAscendingPath">M1875 1011l-787 787v-1798h-128v1798l-787 -787l-90 90l941 941l941 -941z</StreamGeometry>
-    <StreamGeometry x:Key="DataGridSortIconDescendingPath">M1965 947l-941 -941l-941 941l90 90l787 -787v1798h128v-1798l787 787z</StreamGeometry>
+    <StreamGeometry x:Key="DataGridSortIconDescendingPath">M1875 1011l-787 787v-1798h-128v1798l-787 -787l-90 90l941 941l941 -941z</StreamGeometry>
+    <StreamGeometry x:Key="DataGridSortIconAscendingPath">M1965 947l-941 -941l-941 941l90 90l787 -787v1798h128v-1798l787 787z</StreamGeometry>
     <StreamGeometry x:Key="DataGridRowGroupHeaderIconClosedPath">M515 93l930 931l-930 931l90 90l1022 -1021l-1022 -1021z</StreamGeometry>
     <StreamGeometry x:Key="DataGridRowGroupHeaderIconOpenedPath">M1939 1581l90 -90l-1005 -1005l-1005 1005l90 90l915 -915z</StreamGeometry>
 

src/Avalonia.Controls.DataGrid/Utils/ReflectionHelper.cs

@@ -340,10 +340,30 @@ namespace Avalonia.Controls.Utils
         internal static PropertyInfo GetPropertyOrIndexer(this Type type, string propertyPath, out object[] index)
         {
             index = null;
+            // Return the default value of GetProperty if the first character is not an indexer token.
             if (string.IsNullOrEmpty(propertyPath) || propertyPath[0] != LeftIndexerToken)
             {
-                // Return the default value of GetProperty if the first character is not an indexer token.
-                return type.GetProperty(propertyPath);
+                var property = type.GetProperty(propertyPath);
+                if (property != null)
+                {
+                    return property;
+                }
+
+                // GetProperty does not return inherited interface properties,
+                // so we need to enumerate them manually.
+                if (type.IsInterface)
+                {
+                    foreach (var typeInterface in type.GetInterfaces())
+                    {
+                        property = type.GetProperty(propertyPath);
+                        if (property != null)
+                        {
+                            return property;
+                        }
+                    }
+                }
+
+                return null;
             }
 
             if (propertyPath.Length < 2 || propertyPath[propertyPath.Length - 1] != RightIndexerToken)

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -4,11 +4,41 @@ InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalon
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.IMenuItem.StaysOpenOnClick.set(System.Boolean)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.INativeMenuExporterEventsImplBridge.RaiseClosed()' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.INativeMenuExporterEventsImplBridge.RaiseOpening()' is present in the implementation but not in the contract.
+MembersMustExist : Member 'public Avalonia.DirectProperty<Avalonia.Controls.NumericUpDown, System.Double> Avalonia.DirectProperty<Avalonia.Controls.NumericUpDown, System.Double> Avalonia.Controls.NumericUpDown.ValueProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Double> Avalonia.StyledProperty<System.Double> Avalonia.Controls.NumericUpDown.IncrementProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Double> Avalonia.StyledProperty<System.Double> Avalonia.Controls.NumericUpDown.MaximumProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Double> Avalonia.StyledProperty<System.Double> Avalonia.Controls.NumericUpDown.MinimumProperty' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDown.Increment.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDown.Increment.set(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDown.Maximum.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDown.Maximum.set(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDown.Minimum.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDown.Minimum.set(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected System.Double Avalonia.Controls.NumericUpDown.OnCoerceIncrement(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected System.Double Avalonia.Controls.NumericUpDown.OnCoerceMaximum(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected System.Double Avalonia.Controls.NumericUpDown.OnCoerceMinimum(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected System.Double Avalonia.Controls.NumericUpDown.OnCoerceValue(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.NumericUpDown.OnIncrementChanged(System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.NumericUpDown.OnMaximumChanged(System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.NumericUpDown.OnMinimumChanged(System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.NumericUpDown.OnValueChanged(System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Controls.NumericUpDown.RaiseValueChangedEvent(System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDown.Value.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDown.Value.set(System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public void Avalonia.Controls.NumericUpDownValueChangedEventArgs..ctor(Avalonia.Interactivity.RoutedEvent, System.Double, System.Double)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDownValueChangedEventArgs.NewValue.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public System.Double Avalonia.Controls.NumericUpDownValueChangedEventArgs.OldValue.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'public Avalonia.StyledProperty<System.Boolean> Avalonia.StyledProperty<System.Boolean> Avalonia.Controls.ScrollViewer.AllowAutoHideProperty' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.AvaloniaProperty<Avalonia.Media.Stretch> Avalonia.Controls.Viewbox.StretchProperty' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.EventHandler<System.ComponentModel.CancelEventArgs> Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.ShutdownRequested' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.add_ShutdownRequested(System.EventHandler<System.ComponentModel.CancelEventArgs>)' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.remove_ShutdownRequested(System.EventHandler<System.ComponentModel.CancelEventArgs>)' is present in the implementation but not in the contract.
 MembersMustExist : Member 'public void Avalonia.Controls.Embedding.Offscreen.OffscreenTopLevelImplBase.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public Avalonia.AvaloniaProperty Avalonia.AvaloniaProperty Avalonia.Controls.Notifications.NotificationCard.CloseOnClickProperty' does not exist in the implementation but it does exist in the contract.
 EnumValuesMustMatch : Enum value 'Avalonia.Platform.ExtendClientAreaChromeHints Avalonia.Platform.ExtendClientAreaChromeHints.Default' is (System.Int32)2 in the implementation but (System.Int32)1 in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize.get()' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.ICursorImpl)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' is present in the contract but not in the implementation.
 MembersMustExist : Member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
-Total Issues: 12
+Total Issues: 42

src/Avalonia.Controls/Application.cs

@@ -13,6 +13,7 @@ using Avalonia.Platform;
 using Avalonia.Rendering;
 using Avalonia.Styling;
 using Avalonia.Threading;
+#nullable enable
 
 namespace Avalonia
 {
@@ -35,27 +36,27 @@ namespace Avalonia
         /// <summary>
         /// The application-global data templates.
         /// </summary>
-        private DataTemplates _dataTemplates;
+        private DataTemplates? _dataTemplates;
 
         private readonly Lazy<IClipboard> _clipboard =
             new Lazy<IClipboard>(() => (IClipboard)AvaloniaLocator.Current.GetService(typeof(IClipboard)));
         private readonly Styler _styler = new Styler();
-        private Styles _styles;
-        private IResourceDictionary _resources;
+        private Styles? _styles;
+        private IResourceDictionary? _resources;
         private bool _notifyingResourcesChanged;
-        private Action<IReadOnlyList<IStyle>> _stylesAdded;
-        private Action<IReadOnlyList<IStyle>> _stylesRemoved;
+        private Action<IReadOnlyList<IStyle>>? _stylesAdded;
+        private Action<IReadOnlyList<IStyle>>? _stylesRemoved;
 
         /// <summary>
         /// Defines the <see cref="DataContext"/> property.
         /// </summary>
-        public static readonly StyledProperty<object> DataContextProperty =
+        public static readonly StyledProperty<object?> DataContextProperty =
             StyledElement.DataContextProperty.AddOwner<Application>();
 
         /// <inheritdoc/>
-        public event EventHandler<ResourcesChangedEventArgs> ResourcesChanged;
+        public event EventHandler<ResourcesChangedEventArgs>? ResourcesChanged;
 
-        public event EventHandler<UrlOpenedEventArgs> UrlsOpened; 
+        public event EventHandler<UrlOpenedEventArgs>? UrlsOpened; 
 
         /// <summary>
         /// Creates an instance of the <see cref="Application"/> class.
@@ -72,7 +73,7 @@ namespace Avalonia
         /// The data context property specifies the default object that will
         /// be used for data binding.
         /// </remarks>
-        public object DataContext
+        public object? DataContext
         {
             get { return GetValue(DataContextProperty); }
             set { SetValue(DataContextProperty, value); }
@@ -162,7 +163,7 @@ namespace Avalonia
         /// <summary>
         /// Gets the styling parent of the application, which is null.
         /// </summary>
-        IStyleHost IStyleHost.StylingParent => null;
+        IStyleHost? IStyleHost.StylingParent => null;
 
         /// <inheritdoc/>
         bool IStyleHost.IsStylesInitialized => _styles != null;
@@ -194,7 +195,7 @@ namespace Avalonia
         public virtual void Initialize() { }
 
         /// <inheritdoc/>
-        bool IResourceNode.TryGetResource(object key, out object value)
+        bool IResourceNode.TryGetResource(object key, out object? value)
         {
             value = null;
             return (_resources?.TryGetResource(key, out value) ?? false) ||
@@ -279,17 +280,17 @@ namespace Avalonia
             NotifyResourcesChanged(e);
         }
 
-        private string _name;
+        private string? _name;
         /// <summary>
         /// Defines Name property
         /// </summary>
-        public static readonly DirectProperty<Application, string> NameProperty =
-            AvaloniaProperty.RegisterDirect<Application, string>("Name", o => o.Name, (o, v) => o.Name = v);
+        public static readonly DirectProperty<Application, string?> NameProperty =
+            AvaloniaProperty.RegisterDirect<Application, string?>("Name", o => o.Name, (o, v) => o.Name = v);
 
         /// <summary>
         /// Application name to be used for various platform-specific purposes
         /// </summary>
-        public string Name
+        public string? Name
         {
             get => _name;
             set => SetAndRaise(NameProperty, ref _name, value);

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Threading;
 using Avalonia.Controls;
@@ -42,9 +43,13 @@ namespace Avalonia.Controls.ApplicationLifetimes
                     "Can not have multiple active ClassicDesktopStyleApplicationLifetime instances and the previously created one was not disposed");
             _activeLifetime = this;
         }
-        
+
         /// <inheritdoc/>
         public event EventHandler<ControlledApplicationLifetimeStartupEventArgs> Startup;
+
+        /// <inheritdoc/>
+        public event EventHandler<CancelEventArgs> ShutdownRequested;
+
         /// <inheritdoc/>
         public event EventHandler<ControlledApplicationLifetimeExitEventArgs> Exit;
 
@@ -111,6 +116,11 @@ namespace Avalonia.Controls.ApplicationLifetimes
                 ((IApplicationPlatformEvents)Application.Current).RaiseUrlsOpened(args);
             }
 
+            var lifetimeEvents = AvaloniaLocator.Current.GetService<IPlatformLifetimeEventsImpl>(); 
+
+            if (lifetimeEvents != null)
+                lifetimeEvents.ShutdownRequested += OnShutdownRequested;
+
             _cts = new CancellationTokenSource();
             MainWindow?.Show();
             Dispatcher.UIThread.MainLoop(_cts.Token);
@@ -123,6 +133,23 @@ namespace Avalonia.Controls.ApplicationLifetimes
             if (_activeLifetime == this)
                 _activeLifetime = null;
         }
+        
+        private void OnShutdownRequested(object sender, CancelEventArgs e)
+        {
+            ShutdownRequested?.Invoke(this, e);
+
+            if (e.Cancel)
+                return;
+
+            // When an OS shutdown request is received, try to close all non-owned windows. Windows can cancel
+            // shutdown by setting e.Cancel = true in the Closing event. Owned windows will be shutdown by their
+            // owners.
+            foreach (var w in Windows)
+                if (w.Owner is null)
+                    w.Close();
+            if (Windows.Count > 0)
+                e.Cancel = true;
+        }
     }
     
     public class ClassicDesktopStyleApplicationLifetimeOptions

src/Avalonia.Controls/ApplicationLifetimes/IClassicDesktopStyleApplicationLifetime.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 
 namespace Avalonia.Controls.ApplicationLifetimes
 {
@@ -34,5 +35,16 @@ namespace Avalonia.Controls.ApplicationLifetimes
         Window MainWindow { get; set; }
         
         IReadOnlyList<Window> Windows { get; }
+
+        /// <summary>
+        /// Raised by the platform when a shutdown is requested.
+        /// </summary>
+        /// <remarks>
+        /// Raised on on OSX via the Quit menu or right-clicking on the application icon and selecting Quit. This event
+        /// provides a first-chance to cancel application shutdown; if shutdown is not canceled at this point the application
+        /// will try to close each non-owned open window, invoking the <see cref="Window.Closing"/> event on each and allowing
+        /// each window to cancel the shutdown.
+        /// </remarks>
+        event EventHandler<CancelEventArgs> ShutdownRequested;
     }
 }

src/Avalonia.Controls/ComboBox.cs

@@ -77,14 +77,6 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<VerticalAlignment> VerticalContentAlignmentProperty =
             ContentControl.VerticalContentAlignmentProperty.AddOwner<ComboBox>();
 
-        /// <summary>
-        /// Defines the <see cref="IsTextSearchEnabled"/> property.
-        /// </summary>
-        public static readonly StyledProperty<bool> IsTextSearchEnabledProperty =
-            AvaloniaProperty.Register<ComboBox, bool>(nameof(IsTextSearchEnabled), true);
-
-        private string _textSearchTerm = string.Empty;
-        private DispatcherTimer _textSearchTimer;
         private bool _isDropDownOpen;
         private Popup _popup;
         private object _selectionBoxItem;
@@ -99,6 +91,7 @@ namespace Avalonia.Controls
             FocusableProperty.OverrideDefaultValue<ComboBox>(true);
             SelectedItemProperty.Changed.AddClassHandler<ComboBox>((x,e) => x.SelectedItemChanged(e));
             KeyDownEvent.AddClassHandler<ComboBox>((x, e) => x.OnKeyDown(e), Interactivity.RoutingStrategies.Tunnel);
+            IsTextSearchEnabledProperty.OverrideDefaultValue<ComboBox>(true);
         }
 
         /// <summary>
@@ -173,15 +166,6 @@ namespace Avalonia.Controls
             set { SetValue(VerticalContentAlignmentProperty, value); }
         }
 
-        /// <summary>
-        /// Gets or sets a value that specifies whether a user can jump to a value by typing.
-        /// </summary>
-        public bool IsTextSearchEnabled
-        {
-            get { return GetValue(IsTextSearchEnabledProperty); }
-            set { SetValue(IsTextSearchEnabledProperty, value); }
-        }
-
         /// <inheritdoc/>
         protected override IItemContainerGenerator CreateItemContainerGenerator()
         {
@@ -205,7 +189,7 @@ namespace Avalonia.Controls
             if (e.Handled)
                 return;
 
-            if (e.Key == Key.F4 ||
+            if ((e.Key == Key.F4 && e.KeyModifiers.HasAllFlags(KeyModifiers.Alt) == false) ||
                 ((e.Key == Key.Down || e.Key == Key.Up) && e.KeyModifiers.HasAllFlags(KeyModifiers.Alt)))
             {
                 IsDropDownOpen = !IsDropDownOpen;
@@ -247,32 +231,6 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <inheritdoc />
-        protected override void OnTextInput(TextInputEventArgs e)
-        {
-            if (!IsTextSearchEnabled || e.Handled)
-                return;
-
-            StopTextSearchTimer();
-
-            _textSearchTerm += e.Text;
-
-            bool match(ItemContainerInfo info) => 
-                info.ContainerControl is IContentControl control &&
-                control.Content?.ToString()?.StartsWith(_textSearchTerm, StringComparison.OrdinalIgnoreCase) == true;
-
-            var info = ItemContainerGenerator.Containers.FirstOrDefault(match);
-
-            if (info != null)
-            {
-                SelectedIndex = info.Index;
-            }
-
-            StartTextSearchTimer();
-
-            e.Handled = true;
-        }
-
         /// <inheritdoc/>
         protected override void OnPointerWheelChanged(PointerWheelEventArgs e)
         {
@@ -470,31 +428,5 @@ namespace Avalonia.Controls
 
             SelectedIndex = prev;
         }
-
-        private void StartTextSearchTimer()
-        {
-            _textSearchTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
-            _textSearchTimer.Tick += TextSearchTimer_Tick;
-            _textSearchTimer.Start();
-        }
-
-        private void StopTextSearchTimer()
-        {
-            if (_textSearchTimer == null)
-            {
-                return;
-            }
-
-            _textSearchTimer.Stop();
-            _textSearchTimer.Tick -= TextSearchTimer_Tick;
-
-            _textSearchTimer = null;
-        }
-
-        private void TextSearchTimer_Tick(object sender, EventArgs e)
-        {
-            _textSearchTerm = string.Empty;
-            StopTextSearchTimer();
-        }
     }
 }

src/Avalonia.Controls/ContextMenu.cs

@@ -1,12 +1,15 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Linq;
+
 using Avalonia.Controls.Generators;
 using Avalonia.Controls.Platform;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Primitives.PopupPositioning;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
+using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
 using Avalonia.Layout;
 using Avalonia.Styling;
@@ -220,7 +223,8 @@ namespace Avalonia.Controls
 
             if (e.OldValue is ContextMenu oldMenu)
             {
-                control.PointerReleased -= ControlPointerReleased;
+                control.ContextRequested -= ControlContextRequested;
+                control.DetachedFromVisualTree -= ControlDetachedFromVisualTree;
                 oldMenu._attachedControls?.Remove(control);
                 ((ISetLogicalParent?)oldMenu._popup)?.SetParent(null);
             }
@@ -229,7 +233,8 @@ namespace Avalonia.Controls
             {
                 newMenu._attachedControls ??= new List<Control>();
                 newMenu._attachedControls.Add(control);
-                control.PointerReleased += ControlPointerReleased;
+                control.ContextRequested += ControlContextRequested;
+                control.DetachedFromVisualTree += ControlDetachedFromVisualTree;
             }
         }
 
@@ -269,7 +274,7 @@ namespace Avalonia.Controls
             }
 
             control ??= _attachedControls![0];
-            Open(control, PlacementTarget ?? control);
+            Open(control, PlacementTarget ?? control, false);
         }
 
         /// <summary>
@@ -304,7 +309,7 @@ namespace Avalonia.Controls
             return new MenuItemContainerGenerator(this);
         }
 
-        private void Open(Control control, Control placementTarget)
+        private void Open(Control control, Control placementTarget, bool requestedByPointer)
         {
             if (IsOpen)
             {
@@ -329,6 +334,8 @@ namespace Avalonia.Controls
 
                 _popup.Opened += PopupOpened;
                 _popup.Closed += PopupClosed;
+                _popup.Closing += PopupClosing;
+                _popup.KeyUp += PopupKeyUp;
             }
 
             if (_popup.Parent != control)
@@ -337,6 +344,10 @@ namespace Avalonia.Controls
                 ((ISetLogicalParent)_popup).SetParent(control);
             }
 
+            _popup.PlacementMode = !requestedByPointer && PlacementMode == PlacementMode.Pointer
+                ? PlacementMode.Bottom
+                : PlacementMode;
+
             _popup.PlacementTarget = placementTarget;
             _popup.Child = this;
             IsOpen = true;
@@ -355,6 +366,11 @@ namespace Avalonia.Controls
             Focus();
         }
 
+        private void PopupClosing(object sender, CancelEventArgs e)
+        {
+            e.Cancel = CancelClosing();
+        }
+
         private void PopupClosed(object sender, EventArgs e)
         {
             foreach (var i in LogicalChildren)
@@ -383,30 +399,43 @@ namespace Avalonia.Controls
             });
         }
 
-        private static void ControlPointerReleased(object sender, PointerReleasedEventArgs e)
+        private void PopupKeyUp(object sender, KeyEventArgs e)
         {
-            var control = (Control)sender;
-            var contextMenu = control.ContextMenu;
-
-            if (control.ContextMenu.IsOpen)
+            if (IsOpen)
             {
-                if (contextMenu.CancelClosing())
-                    return;
+                var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>();
 
-                control.ContextMenu.Close();
-                e.Handled = true;
+                if (keymap.OpenContextMenu.Any(k => k.Matches(e))
+                    && !CancelClosing())
+                {
+                    Close();
+                    e.Handled = true;
+                }
             }
+        }
 
-            if (e.InitialPressMouseButton == MouseButton.Right)
+        private static void ControlContextRequested(object sender, ContextRequestedEventArgs e)
+        {
+            if (sender is Control control
+                && control.ContextMenu is ContextMenu contextMenu
+                && !e.Handled
+                && !contextMenu.CancelOpening())
             {
-                if (contextMenu.CancelOpening())
-                    return;
-
-                contextMenu.Open(control, e.Source as Control ?? control);
+                var requestedByPointer = e.TryGetPosition(null, out _);
+                contextMenu.Open(control, e.Source as Control ?? control, requestedByPointer);
                 e.Handled = true;
             }
         }
 
+        private static void ControlDetachedFromVisualTree(object sender, VisualTreeAttachmentEventArgs e)
+        {
+            if (sender is Control control
+                && control.ContextMenu is ContextMenu contextMenu)
+            {
+                contextMenu.Close();
+            }
+        }
+
         private bool CancelClosing()
         {
             var eventArgs = new CancelEventArgs();

src/Avalonia.Controls/ContextRequestedEventArgs.cs

@@ -0,0 +1,58 @@
+using Avalonia.Input;
+using Avalonia.Interactivity;
+
+#nullable enable
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Provides event data for the ContextRequested event.
+    /// </summary>
+    public class ContextRequestedEventArgs : RoutedEventArgs
+    {
+        private readonly PointerEventArgs? _pointerEventArgs;
+
+        /// <summary>
+        /// Initializes a new instance of the ContextRequestedEventArgs class.
+        /// </summary>
+        public ContextRequestedEventArgs()
+            : base(Control.ContextRequestedEvent)
+        {
+
+        }
+
+        /// <inheritdoc cref="ContextRequestedEventArgs()" />
+        public ContextRequestedEventArgs(PointerEventArgs pointerEventArgs)
+            : this()
+        {
+            _pointerEventArgs = pointerEventArgs;
+        }
+
+        /// <summary>
+        /// Gets the x- and y-coordinates of the pointer position, optionally evaluated against a coordinate origin of a supplied <see cref="Control"/>.
+        /// </summary>
+        /// <param name="relativeTo">
+        /// Any <see cref="Control"/>-derived object that is connected to the same object tree.
+        /// To specify the object relative to the overall coordinate system, use a relativeTo  value of null.
+        /// </param>
+        /// <param name="point">
+        /// A <see cref="Point"/> that represents the current x- and y-coordinates of the mouse pointer position.
+        /// If null was passed as relativeTo, this coordinate is for the overall window.
+        /// If a relativeTo value other than null was passed, this coordinate is relative to the object referenced by relativeTo.
+        /// </param>
+        /// <returns>
+        /// true if the context request was initiated by a pointer device; otherwise, false.
+        /// </returns>
+        public bool TryGetPosition(Control? relativeTo, out Point point)
+        {
+            if (_pointerEventArgs is null)
+            {
+                point = default;
+                return false;
+            }
+
+            point = _pointerEventArgs.GetPosition(relativeTo);
+            return true;
+        }
+    }
+}

src/Avalonia.Controls/Control.cs

@@ -3,6 +3,7 @@ using System.ComponentModel;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
+using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
 using Avalonia.Rendering;
 using Avalonia.Styling;
@@ -19,6 +20,7 @@ namespace Avalonia.Controls
     /// The control class extends <see cref="InputElement"/> and adds the following features:
     ///
     /// - A <see cref="Tag"/> property to allow user-defined data to be attached to the control.
+    /// - <see cref="ContextRequestedEvent"/> and other context menu related members.
     /// </remarks>
     public class Control : InputElement, IControl, INamed, IVisualBrushInitialize, ISetterValue
     {
@@ -52,6 +54,13 @@ namespace Avalonia.Controls
         public static readonly RoutedEvent<RequestBringIntoViewEventArgs> RequestBringIntoViewEvent =
             RoutedEvent.Register<Control, RequestBringIntoViewEventArgs>("RequestBringIntoView", RoutingStrategies.Bubble);
 
+        /// <summary>
+        /// Provides event data for the <see cref="ContextRequested"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<ContextRequestedEventArgs> ContextRequestedEvent =
+            RoutedEvent.Register<Control, ContextRequestedEventArgs>(nameof(ContextRequested),
+                RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
+
         private DataTemplates? _dataTemplates;
         private IControl? _focusAdorner;
 
@@ -100,6 +109,15 @@ namespace Avalonia.Controls
             set => SetValue(TagProperty, value);
         }
 
+        /// <summary>
+        /// Occurs when the user has completed a context input gesture, such as a right-click.
+        /// </summary>
+        public event EventHandler<ContextRequestedEventArgs> ContextRequested
+        {
+            add => AddHandler(ContextRequestedEvent, value);
+            remove => RemoveHandler(ContextRequestedEvent, value);
+        }
+
         public new IControl? Parent => (IControl?)base.Parent;
 
         /// <inheritdoc/>
@@ -208,5 +226,49 @@ namespace Avalonia.Controls
                 _focusAdorner = null;
             }
         }
+
+        protected override void OnPointerReleased(PointerReleasedEventArgs e)
+        {
+            base.OnPointerReleased(e);
+
+            if (e.Source == this
+                && !e.Handled
+                && e.InitialPressMouseButton == MouseButton.Right)
+            {
+                var args = new ContextRequestedEventArgs(e);
+                RaiseEvent(args);
+                e.Handled = args.Handled;
+            }
+        }
+
+        protected override void OnKeyUp(KeyEventArgs e)
+        {
+            base.OnKeyUp(e);
+
+            if (e.Source == this
+                && !e.Handled)
+            {
+                var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>().OpenContextMenu;
+                var matches = false;
+
+                for (var index = 0; index < keymap.Count; index++)
+                {
+                    var key = keymap[index];
+                    matches |= key.Matches(e);
+
+                    if (matches)
+                    {
+                        break;
+                    }
+                }
+
+                if (matches)
+                {
+                    var args = new ContextRequestedEventArgs();
+                    RaiseEvent(args);
+                    e.Handled = args.Handled;
+                }
+            }
+        }
     }
 }

src/Avalonia.Controls/DateTimePickers/DatePicker.cs

@@ -2,6 +2,7 @@
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
+using Avalonia.Data;
 using Avalonia.Interactivity;
 using System;
 using System.Collections.Generic;
@@ -88,7 +89,8 @@ namespace Avalonia.Controls
         /// </summary>
         public static readonly DirectProperty<DatePicker, DateTimeOffset?> SelectedDateProperty =
             AvaloniaProperty.RegisterDirect<DatePicker, DateTimeOffset?>(nameof(SelectedDate), 
-                x => x.SelectedDate, (x, v) => x.SelectedDate = v);
+                x => x.SelectedDate, (x, v) => x.SelectedDate = v,
+                defaultBindingMode: BindingMode.TwoWay);
 
         // Template Items
         private Button _flyoutButton;

src/Avalonia.Controls/DateTimePickers/TimePicker.cs

@@ -2,6 +2,7 @@
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
+using Avalonia.Data;
 using System;
 using System.Globalization;
 
@@ -44,7 +45,8 @@ namespace Avalonia.Controls
         /// </summary>
         public static readonly DirectProperty<TimePicker, TimeSpan?> SelectedTimeProperty =
             AvaloniaProperty.RegisterDirect<TimePicker, TimeSpan?>(nameof(SelectedTime),
-                x => x.SelectedTime, (x, v) => x.SelectedTime = v);
+                x => x.SelectedTime, (x, v) => x.SelectedTime = v,
+                defaultBindingMode: BindingMode.TwoWay);
 
         // Template Items
         private TimePickerPresenter _presenter;

src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs

@@ -35,6 +35,8 @@ namespace Avalonia.Controls.Embedding.Offscreen
             }
         }
 
+        public Size? FrameSize => null;
+
         public double RenderScaling
         {
             get { return _scaling; }

src/Avalonia.Controls/Expander.cs

@@ -1,7 +1,11 @@
+using System.Threading;
+
 using Avalonia.Animation;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 
+#nullable enable
+
 namespace Avalonia.Controls
 {
     /// <summary>
@@ -36,8 +40,8 @@ namespace Avalonia.Controls
     [PseudoClasses(":expanded", ":up", ":down", ":left", ":right")]
     public class Expander : HeaderedContentControl
     {
-        public static readonly StyledProperty<IPageTransition> ContentTransitionProperty =
-            AvaloniaProperty.Register<Expander, IPageTransition>(nameof(ContentTransition));
+        public static readonly StyledProperty<IPageTransition?> ContentTransitionProperty =
+            AvaloniaProperty.Register<Expander, IPageTransition?>(nameof(ContentTransition));
 
         public static readonly StyledProperty<ExpandDirection> ExpandDirectionProperty =
             AvaloniaProperty.Register<Expander, ExpandDirection>(nameof(ExpandDirection), ExpandDirection.Down);
@@ -50,6 +54,7 @@ namespace Avalonia.Controls
                 defaultBindingMode: Data.BindingMode.TwoWay);
 
         private bool _isExpanded;
+        private CancellationTokenSource? _lastTransitionCts;
 
         static Expander()
         {
@@ -61,7 +66,7 @@ namespace Avalonia.Controls
             UpdatePseudoClasses(ExpandDirection);
         }
 
-        public IPageTransition ContentTransition
+        public IPageTransition? ContentTransition
         {
             get => GetValue(ContentTransitionProperty);
             set => SetValue(ContentTransitionProperty, value);
@@ -83,19 +88,23 @@ namespace Avalonia.Controls
             }
         }
 
-        protected virtual void OnIsExpandedChanged(AvaloniaPropertyChangedEventArgs e)
+        protected virtual async void OnIsExpandedChanged(AvaloniaPropertyChangedEventArgs e)
         {
             if (Content != null && ContentTransition != null && Presenter is Visual visualContent)
             {
                 bool forward = ExpandDirection == ExpandDirection.Left ||
                                 ExpandDirection == ExpandDirection.Up;
+
+                _lastTransitionCts?.Cancel();
+                _lastTransitionCts = new CancellationTokenSource();
+
                 if (IsExpanded)
                 {
-                    ContentTransition.Start(null, visualContent, forward);
+                    await ContentTransition.Start(null, visualContent, forward, _lastTransitionCts.Token);
                 }
                 else
                 {
-                    ContentTransition.Start(visualContent, null, !forward);
+                    await ContentTransition.Start(visualContent, null, forward, _lastTransitionCts.Token);
                 }
             }
         }

src/Avalonia.Controls/ExperimentalAcrylicBorder.cs

@@ -3,6 +3,7 @@ using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.Platform;
 using System;
+using Avalonia.Media.Immutable;
 
 namespace Avalonia.Controls
 {
@@ -90,7 +91,7 @@ namespace Avalonia.Controls
             }
             else
             {
-                _borderRenderHelper.Render(context, Bounds.Size, new Thickness(), CornerRadius, new SolidColorBrush(Material.FallbackColor), null, default);
+                _borderRenderHelper.Render(context, Bounds.Size, new Thickness(), CornerRadius, new ImmutableSolidColorBrush(Material.FallbackColor), null, default);
             }
         }
 

src/Avalonia.Controls/Flyouts/FlyoutBase.cs

@@ -1,9 +1,13 @@
 using System;
 using System.ComponentModel;
+using System.Linq;
+
 using Avalonia.Input;
+using Avalonia.Input.Platform;
 using Avalonia.Input.Raw;
 using Avalonia.Layout;
 using Avalonia.Logging;
+using Avalonia.Rendering;
 
 #nullable enable
 
@@ -48,13 +52,20 @@ namespace Avalonia.Controls.Primitives
         public static readonly AttachedProperty<FlyoutBase?> AttachedFlyoutProperty =
             AvaloniaProperty.RegisterAttached<FlyoutBase, Control, FlyoutBase?>("AttachedFlyout", null);
 
+        private readonly Lazy<Popup> _popupLazy;
         private bool _isOpen;
         private Control? _target;
         private FlyoutShowMode _showMode = FlyoutShowMode.Standard;
-        private Rect? enlargedPopupRect;
-        private IDisposable? transientDisposable;
+        private Rect? _enlargedPopupRect;
+        private PixelRect? _enlargePopupRectScreenPixelRect;
+        private IDisposable? _transientDisposable;
+
+        public FlyoutBase()
+        {
+            _popupLazy = new Lazy<Popup>(() => CreatePopup());
+        }
 
-        protected Popup? Popup { get; private set; }
+        protected Popup Popup => _popupLazy.Value;
 
         /// <summary>
         /// Gets whether this Flyout is currently Open
@@ -140,22 +151,19 @@ namespace Avalonia.Controls.Primitives
             HideCore();
         }
 
-        protected virtual void HideCore(bool canCancel = true)
+        /// <returns>True, if action was handled</returns>
+        protected virtual bool HideCore(bool canCancel = true)
         {
             if (!IsOpen)
             {
-                return;
+                return false;
             }
 
             if (canCancel)
             {
-                bool cancel = false;
-
-                var closing = new CancelEventArgs();
-                Closing?.Invoke(this, closing);
-                if (cancel || closing.Cancel)
+                if (CancelClosing())
                 {
-                    return;
+                    return false;
                 }
             }
 
@@ -163,34 +171,47 @@ namespace Avalonia.Controls.Primitives
             Popup.IsOpen = false;
 
             // Ensure this isn't active
-            transientDisposable?.Dispose();
-            transientDisposable = null;
+            _transientDisposable?.Dispose();
+            _transientDisposable = null;
+            _enlargedPopupRect = null;
+            _enlargePopupRectScreenPixelRect = null;
+
+            if (Target != null)
+            {
+                Target.DetachedFromVisualTree -= PlacementTarget_DetachedFromVisualTree;
+                Target.KeyUp -= OnPlacementTargetOrPopupKeyUp;
+            }
 
             OnClosed();
+
+            return true;
         }
 
-        protected virtual void ShowAtCore(Control placementTarget, bool showAtPointer = false)
+        /// <returns>True, if action was handled</returns>
+        protected virtual bool ShowAtCore(Control placementTarget, bool showAtPointer = false)
         {
             if (placementTarget == null)
-                throw new ArgumentNullException("placementTarget cannot be null");
-
-            if (Popup == null)
             {
-                InitPopup();
+                throw new ArgumentNullException(nameof(placementTarget));
             }
 
             if (IsOpen)
             {
                 if (placementTarget == Target)
                 {
-                    return;
+                    return false;
                 }
                 else // Close before opening a new one
                 {
-                    HideCore(false);
+                    _ = HideCore(false);
                 }
             }
 
+            if (CancelOpening())
+            {
+                return false;
+            }
+
             if (Popup.Parent != null && Popup.Parent != placementTarget)
             {
                 ((ISetLogicalParent)Popup).SetParent(null);
@@ -207,11 +228,13 @@ namespace Avalonia.Controls.Primitives
                 Popup.Child = CreatePresenter();
             }
 
-            OnOpening();
             PositionPopup(showAtPointer);
-            IsOpen = Popup.IsOpen = true;            
+            IsOpen = Popup.IsOpen = true;
             OnOpened();
-                        
+
+            placementTarget.DetachedFromVisualTree += PlacementTarget_DetachedFromVisualTree;
+            placementTarget.KeyUp += OnPlacementTargetOrPopupKeyUp;
+
             if (ShowMode == FlyoutShowMode.Standard)
             {
                 // Try and focus content inside Flyout
@@ -230,8 +253,15 @@ namespace Avalonia.Controls.Primitives
             }
             else if (ShowMode == FlyoutShowMode.TransientWithDismissOnPointerMoveAway)
             {
-                transientDisposable = InputManager.Instance?.Process.Subscribe(HandleTransientDismiss);
+                _transientDisposable = InputManager.Instance?.Process.Subscribe(HandleTransientDismiss);
             }
+
+            return true;
+        }
+
+        private void PlacementTarget_DetachedFromVisualTree(object sender, VisualTreeAttachmentEventArgs e)
+        {
+            _ = HideCore(false);
         }
 
         private void HandleTransientDismiss(RawInputEventArgs args)
@@ -246,20 +276,20 @@ namespace Avalonia.Controls.Primitives
                 // For windowed popups, enlargedPopupRect is in screen coordinates,
                 // for overlay popups, its in OverlayLayer coordinates
 
-                if (enlargedPopupRect == null)
+                if (_enlargedPopupRect == null && _enlargePopupRectScreenPixelRect == null)
                 {
                     // Only do this once when the Flyout opens & cache the result
                     if (Popup?.Host is PopupRoot root)
-                    { 
+                    {
                         // Get the popup root bounds and convert to screen coordinates
+                        
                         var tmp = root.Bounds.Inflate(100);
-                        var scPt = root.PointToScreen(tmp.TopLeft);
-                        enlargedPopupRect = new Rect(scPt.X, scPt.Y, tmp.Width, tmp.Height);
+                        _enlargePopupRectScreenPixelRect = new PixelRect(root.PointToScreen(tmp.TopLeft), root.PointToScreen(tmp.BottomRight));
                     }
                     else if (Popup?.Host is OverlayPopupHost host)
                     {
                         // Overlay popups are in OverlayLayer coordinates, just use that
-                        enlargedPopupRect = host.Bounds.Inflate(100);
+                        _enlargedPopupRect = host.Bounds.Inflate(100);
                     }
 
                     return;
@@ -273,32 +303,26 @@ namespace Avalonia.Controls.Primitives
                     // window will not close this (as pointer events stop), which 
                     // does match UWP
                     var pt = pArgs.Root.PointToScreen(pArgs.Position);
-                    if (!enlargedPopupRect?.Contains(new Point(pt.X, pt.Y)) ?? false)
+                    if (!_enlargePopupRectScreenPixelRect?.Contains(pt) ?? false)
                     {
                         HideCore(false);
-                        enlargedPopupRect = null;
-                        transientDisposable?.Dispose();
-                        transientDisposable = null;
                     }
                 }
                 else if (Popup?.Host is OverlayPopupHost)
                 {
                     // Same as above here, but just different coordinate space
                     // so we don't need to translate
-                    if (!enlargedPopupRect?.Contains(pArgs.Position) ?? false)
+                    if (!_enlargedPopupRect?.Contains(pArgs.Position) ?? false)
                     {
                         HideCore(false);
-                        enlargedPopupRect = null;
-                        transientDisposable?.Dispose();
-                        transientDisposable = null;
                     }
                 }
             }
         }
 
-        protected virtual void OnOpening()
+        protected virtual void OnOpening(CancelEventArgs args)
         {
-            Opening?.Invoke(this, null);
+            Opening?.Invoke(this, args);
         }
 
         protected virtual void OnOpened()
@@ -322,14 +346,18 @@ namespace Avalonia.Controls.Primitives
         /// <returns></returns>
         protected abstract Control CreatePresenter();
 
-        private void InitPopup()
+        private Popup CreatePopup()
         {
-            Popup = new Popup();
-            Popup.WindowManagerAddShadowHint = false;
-            Popup.IsLightDismissEnabled = true;
-
-            Popup.Opened += OnPopupOpened;
-            Popup.Closed += OnPopupClosed;
+            var popup = new Popup();
+            popup.WindowManagerAddShadowHint = false;
+            popup.IsLightDismissEnabled = true;
+            popup.OverlayDismissEventPassThrough = true;
+
+            popup.Opened += OnPopupOpened;
+            popup.Closed += OnPopupClosed;
+            popup.Closing += OnPopupClosing;
+            popup.KeyUp += OnPlacementTargetOrPopupKeyUp;
+            return popup;
         }
 
         private void OnPopupOpened(object sender, EventArgs e)
@@ -337,15 +365,40 @@ namespace Avalonia.Controls.Primitives
             IsOpen = true;
         }
 
+        private void OnPopupClosing(object sender, CancelEventArgs e)
+        {
+            if (IsOpen)
+            {
+                e.Cancel = CancelClosing();
+            }
+        }
+
         private void OnPopupClosed(object sender, EventArgs e)
         {
-            HideCore();
+            HideCore(false);
+        }
+
+        // This method is handling both popup logical tree and target logical tree.
+        private void OnPlacementTargetOrPopupKeyUp(object sender, KeyEventArgs e)
+        {
+            if (!e.Handled
+                && IsOpen
+                && Target?.ContextFlyout == this)
+            {
+                var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>();
+
+                if (keymap.OpenContextMenu.Any(k => k.Matches(e)))
+                {
+                    e.Handled = HideCore();
+                }
+            }
         }
 
         private void PositionPopup(bool showAtPointer)
         {
             Size sz;
-            if(Popup.Child.DesiredSize == Size.Empty)
+            // Popup.Child can't be null here, it was set in ShowAtCore.
+            if (Popup.Child!.DesiredSize == Size.Empty)
             {
                 // Popup may not have been shown yet. Measure content
                 sz = LayoutHelper.MeasureChild(Popup.Child, Size.Infinity, new Thickness());
@@ -372,19 +425,19 @@ namespace Avalonia.Controls.Primitives
             switch (Placement)
             {
                 case FlyoutPlacementMode.Top: //Above & centered
-                    Popup.PlacementRect = new Rect(0, 0, trgtBnds.Width-1, 1);
+                    Popup.PlacementRect = new Rect(0, 0, trgtBnds.Width - 1, 1);
                     Popup.PlacementGravity = PopupPositioning.PopupGravity.Top;
                     Popup.PlacementAnchor = PopupPositioning.PopupAnchor.Top;
                     break;
 
                 case FlyoutPlacementMode.TopEdgeAlignedLeft:
                     Popup.PlacementRect = new Rect(0, 0, 0, 0);
-                    Popup.PlacementGravity = PopupPositioning.PopupGravity.TopRight;                    
+                    Popup.PlacementGravity = PopupPositioning.PopupGravity.TopRight;
                     break;
 
                 case FlyoutPlacementMode.TopEdgeAlignedRight:
                     Popup.PlacementRect = new Rect(trgtBnds.Width - 1, 0, 10, 1);
-                    Popup.PlacementGravity = PopupPositioning.PopupGravity.TopLeft;                    
+                    Popup.PlacementGravity = PopupPositioning.PopupGravity.TopLeft;
                     break;
 
                 case FlyoutPlacementMode.RightEdgeAlignedTop:
@@ -456,33 +509,45 @@ namespace Avalonia.Controls.Primitives
             {
                 if (args.OldValue is FlyoutBase)
                 {
-                    c.PointerReleased -= OnControlWithContextFlyoutPointerReleased;
+                    c.ContextRequested -= OnControlContextRequested;
                 }
                 if (args.NewValue is FlyoutBase)
                 {
-                    c.PointerReleased += OnControlWithContextFlyoutPointerReleased;
+                    c.ContextRequested += OnControlContextRequested;
                 }
             }
         }
 
-        private static void OnControlWithContextFlyoutPointerReleased(object sender, PointerReleasedEventArgs e)
+        private static void OnControlContextRequested(object sender, ContextRequestedEventArgs e)
         {
-            if (sender is Control c)
+            var control = (Control)sender;
+            if (!e.Handled
+                && control.ContextFlyout is FlyoutBase flyout)
             {
-                if (e.InitialPressMouseButton == MouseButton.Right &&
-                e.GetCurrentPoint(c).Properties.PointerUpdateKind == PointerUpdateKind.RightButtonReleased)
+                if (control.ContextMenu != null)
                 {
-                    if (c.ContextFlyout != null)
-                    {
-                        if (c.ContextMenu != null)
-                        {
-                            Logger.TryGet(LogEventLevel.Verbose, "FlyoutBase")?.Log(c, "ContextMenu and ContextFlyout are both set, defaulting to ContextMenu");
-                            return;
-                        }
-                        c.ContextFlyout.ShowAt(c, true);
-                    }
+                    Logger.TryGet(LogEventLevel.Verbose, "FlyoutBase")?.Log(control, "ContextMenu and ContextFlyout are both set, defaulting to ContextMenu");
+                    return;
                 }
-            }            
+
+                // We do not support absolute popup positioning yet, so we ignore "point" at this moment.
+                var triggeredByPointerInput = e.TryGetPosition(null, out _);
+                e.Handled = flyout.ShowAtCore(control, triggeredByPointerInput);
+            }
+        }
+
+        private bool CancelClosing()
+        {
+            var eventArgs = new CancelEventArgs();
+            OnClosing(eventArgs);
+            return eventArgs.Cancel;
+        }
+
+        private bool CancelOpening()
+        {
+            var eventArgs = new CancelEventArgs();
+            OnOpening(eventArgs);
+            return eventArgs.Cancel;
         }
 
         internal static void SetPresenterClasses(IControl presenter, Classes classes)

src/Avalonia.Controls/Flyouts/FlyoutShowMode.cs

@@ -12,7 +12,7 @@
         Standard,
 
         /// <summary>
-        /// Behavior is typical of a flyout shown proactively. The open flyout does not take focus. For a CommandBarFlyout, it opens in it's collapsed state.
+        /// Behavior is typical of a flyout shown proactively. The open flyout does not take focus.
         /// </summary>
         Transient,
 

src/Avalonia.Controls/Flyouts/MenuFlyoutPresenter.cs

@@ -29,16 +29,8 @@ namespace Avalonia.Controls
             var host = this.FindLogicalAncestorOfType<Popup>();
             if (host != null)
             {
-                for (int i = 0; i < LogicalChildren.Count; i++)
-                {
-                    if (LogicalChildren[i] is MenuItem item)
-                    {
-                        item.IsSubMenuOpen = false;
-                    }
-                }
-
                 SelectedIndex = -1;
-                host.IsOpen = false;                
+                host.IsOpen = false;
             }
         }
 

src/Avalonia.Controls/Grid.cs

@@ -978,6 +978,7 @@ namespace Avalonia.Controls
         /// width is not registered in columns.</param>
         /// <param name="forceInfinityV">Passed through to MeasureCell.
         /// When "true" cells' desired height is not registered in rows.</param>
+        /// <param name="hasDesiredSizeUChanged">return true when desired size has changed</param>
         private void MeasureCellsGroup(
             int cellsHead,
             Size referenceSize,

src/Avalonia.Controls/GridLength.cs

@@ -77,6 +77,12 @@ namespace Avalonia.Controls
         /// </summary>
         public static GridLength Auto => new GridLength(0, GridUnitType.Auto);
 
+        /// <summary>
+        /// Gets an instance of <see cref="GridLength"/> that indicates that a row or column should
+        /// fill its content.
+        /// </summary>
+        public static GridLength Star => new GridLength(1, GridUnitType.Star);
+
         /// <summary>
         /// Gets the unit of the <see cref="GridLength"/>.
         /// </summary>

src/Avalonia.Controls/ItemsControl.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls.Generators;
 using Avalonia.Controls.Metadata;

src/Avalonia.Controls/Menu.cs

@@ -17,7 +17,6 @@ namespace Avalonia.Controls
         private static readonly ITemplate<IPanel> DefaultPanel =
             new FuncTemplate<IPanel>(() => new StackPanel { Orientation = Orientation.Horizontal });
 
-        private LightDismissOverlayLayer? _overlay;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="Menu"/> class.

src/Avalonia.Controls/MenuItem.cs

@@ -36,7 +36,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="HotKey"/> property.
         /// </summary>
-        public static readonly StyledProperty<KeyGesture> HotKeyProperty =
+        public static readonly StyledProperty<KeyGesture?> HotKeyProperty =
             HotKeyManager.HotKeyProperty.AddOwner<MenuItem>();
 
         /// <summary>
@@ -108,7 +108,7 @@ namespace Avalonia.Controls
         private ICommand? _command;
         private bool _commandCanExecute = true;
         private Popup? _popup;
-        private KeyGesture _hotkey;
+        private KeyGesture? _hotkey;
         private bool _isEmbeddedInMenu;
 
         /// <summary>
@@ -214,7 +214,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets an <see cref="KeyGesture"/> associated with this control
         /// </summary>
-        public KeyGesture HotKey
+        public KeyGesture? HotKey
         {
             get { return GetValue(HotKeyProperty); }
             set { SetValue(HotKeyProperty, value); }

src/Avalonia.Controls/NumericUpDown/NumericUpDown.cs

@@ -45,10 +45,18 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="CultureInfo"/> property.
         /// </summary>
+        [Obsolete]
         public static readonly DirectProperty<NumericUpDown, CultureInfo> CultureInfoProperty =
             AvaloniaProperty.RegisterDirect<NumericUpDown, CultureInfo>(nameof(CultureInfo), o => o.CultureInfo,
                 (o, v) => o.CultureInfo = v, CultureInfo.CurrentCulture);
 
+        /// <summary>
+        /// Defines the <see cref="NumberFormat"/> property.
+        /// </summary>
+        public static readonly DirectProperty<NumericUpDown, NumberFormatInfo> NumberFormatProperty =
+            AvaloniaProperty.RegisterDirect<NumericUpDown, NumberFormatInfo>(nameof(NumberFormat), o => o.NumberFormat,
+                (o, v) => o.NumberFormat = v, NumberFormatInfo.CurrentInfo);
+
         /// <summary>
         /// Defines the <see cref="FormatString"/> property.
         /// </summary>
@@ -58,8 +66,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Increment"/> property.
         /// </summary>
-        public static readonly StyledProperty<double> IncrementProperty =
-            AvaloniaProperty.Register<NumericUpDown, double>(nameof(Increment), 1.0d, coerce: OnCoerceIncrement);
+        public static readonly StyledProperty<decimal> IncrementProperty =
+            AvaloniaProperty.Register<NumericUpDown, decimal>(nameof(Increment), 1.0m, coerce: OnCoerceIncrement);
 
         /// <summary>
         /// Defines the <see cref="IsReadOnly"/> property.
@@ -70,14 +78,14 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Maximum"/> property.
         /// </summary>
-        public static readonly StyledProperty<double> MaximumProperty =
-            AvaloniaProperty.Register<NumericUpDown, double>(nameof(Maximum), double.MaxValue, coerce: OnCoerceMaximum);
+        public static readonly StyledProperty<decimal> MaximumProperty =
+            AvaloniaProperty.Register<NumericUpDown, decimal>(nameof(Maximum), decimal.MaxValue, coerce: OnCoerceMaximum);
 
         /// <summary>
         /// Defines the <see cref="Minimum"/> property.
         /// </summary>
-        public static readonly StyledProperty<double> MinimumProperty =
-            AvaloniaProperty.Register<NumericUpDown, double>(nameof(Minimum), double.MinValue, coerce: OnCoerceMinimum);
+        public static readonly StyledProperty<decimal> MinimumProperty =
+            AvaloniaProperty.Register<NumericUpDown, decimal>(nameof(Minimum), decimal.MinValue, coerce: OnCoerceMinimum);
 
         /// <summary>
         /// Defines the <see cref="ParsingNumberStyle"/> property.
@@ -96,8 +104,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Value"/> property.
         /// </summary>
-        public static readonly DirectProperty<NumericUpDown, double> ValueProperty =
-            AvaloniaProperty.RegisterDirect<NumericUpDown, double>(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>
@@ -106,7 +114,6 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<string> WatermarkProperty =
             AvaloniaProperty.Register<NumericUpDown, string>(nameof(Watermark));
 
-
         /// <summary>
         /// Defines the <see cref="HorizontalContentAlignment"/> property.
         /// </summary>
@@ -121,7 +128,7 @@ namespace Avalonia.Controls
 
         private IDisposable _textBoxTextChangedSubscription;
 
-        private double _value;
+        private decimal _value;
         private string _text;
         private bool _internalValueSet;
         private bool _clipValueToMinMax;
@@ -129,7 +136,8 @@ namespace Avalonia.Controls
         private bool _isTextChangedFromUI;
         private CultureInfo _cultureInfo;
         private NumberStyles _parsingNumberStyle = NumberStyles.Any;
-        
+        private NumberFormatInfo _numberFormat;
+
         /// <summary>
         /// Gets the Spinner template part.
         /// </summary>
@@ -179,10 +187,25 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the current CultureInfo.
         /// </summary>
+        [Obsolete("CultureInfo is obsolete, please use NumberFormat instead.")]
         public CultureInfo CultureInfo
         {
             get { return _cultureInfo; }
-            set { SetAndRaise(CultureInfoProperty, ref _cultureInfo, value); }
+            set
+            {
+                SetAndRaise(CultureInfoProperty, ref _cultureInfo, value);
+                //Set and Raise the NumberFormatProperty when CultureInfo is changed.
+                SetAndRaise(NumberFormatProperty, ref _numberFormat, value?.NumberFormat);
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the current NumberFormatInfo
+        /// </summary>
+        public NumberFormatInfo NumberFormat
+        {
+            get { return _numberFormat; }
+            set { SetAndRaise(NumberFormatProperty, ref _numberFormat, value); }
         }
 
         /// <summary>
@@ -197,7 +220,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the amount in which to increment the <see cref="Value"/>.
         /// </summary>
-        public double Increment
+        public decimal Increment
         {
             get { return GetValue(IncrementProperty); }
             set { SetValue(IncrementProperty, value); }
@@ -215,7 +238,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the maximum allowed value.
         /// </summary>
-        public double Maximum
+        public decimal Maximum
         {
             get { return GetValue(MaximumProperty); }
             set { SetValue(MaximumProperty, value); }
@@ -224,7 +247,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the minimum allowed value.
         /// </summary>
-        public double Minimum
+        public decimal Minimum
         {
             get { return GetValue(MinimumProperty); }
             set { SetValue(MinimumProperty, value); }
@@ -251,7 +274,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the value.
         /// </summary>
-        public double Value
+        public decimal Value
         {
             get { return _value; }
             set
@@ -270,7 +293,6 @@ namespace Avalonia.Controls
             set { SetValue(WatermarkProperty, value); }
         }
 
-
         /// <summary>
         /// Gets or sets the horizontal alignment of the content within the control.
         /// </summary>
@@ -311,6 +333,7 @@ namespace Avalonia.Controls
         static NumericUpDown()
         {
             CultureInfoProperty.Changed.Subscribe(OnCultureInfoChanged);
+            NumberFormatProperty.Changed.Subscribe(OnNumberFormatChanged);
             FormatStringProperty.Changed.Subscribe(FormatStringChanged);
             IncrementProperty.Changed.Subscribe(IncrementChanged);
             IsReadOnlyProperty.Changed.Subscribe(OnIsReadOnlyChanged);
@@ -397,6 +420,19 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Called when the <see cref="NumberFormat"/> property value changed.
+        /// </summary>
+        /// <param name="oldValue">The old value.</param>
+        /// <param name="newValue">The new value.</param>
+        protected virtual void OnNumberFormatChanged(NumberFormatInfo oldValue, NumberFormatInfo newValue)
+        {
+            if (IsInitialized)
+            {
+                SyncTextAndValueProperties(false, null);
+            }
+        }
+
         /// <summary>
         /// Called when the <see cref="FormatString"/> property value changed.
         /// </summary>
@@ -415,7 +451,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void OnIncrementChanged(double oldValue, double newValue)
+        protected virtual void OnIncrementChanged(decimal oldValue, decimal newValue)
         {
             if (IsInitialized)
             {
@@ -438,7 +474,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void OnMaximumChanged(double oldValue, double newValue)
+        protected virtual void OnMaximumChanged(decimal oldValue, decimal newValue)
         {
             if (IsInitialized)
             {
@@ -455,7 +491,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void OnMinimumChanged(double oldValue, double newValue)
+        protected virtual void OnMinimumChanged(decimal oldValue, decimal newValue)
         {
             if (IsInitialized)
             {
@@ -485,7 +521,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void OnValueChanged(double oldValue, double newValue)
+        protected virtual void OnValueChanged(decimal oldValue, decimal newValue)
         {
             if (!_internalValueSet && IsInitialized)
             {
@@ -501,7 +537,7 @@ namespace Avalonia.Controls
         /// Called when the <see cref="Increment"/> property has to be coerced.
         /// </summary>
         /// <param name="baseValue">The value.</param>
-        protected virtual double OnCoerceIncrement(double baseValue)
+        protected virtual decimal OnCoerceIncrement(decimal baseValue)
         {
             return baseValue;
         }
@@ -510,7 +546,7 @@ namespace Avalonia.Controls
         /// Called when the <see cref="Maximum"/> property has to be coerced.
         /// </summary>
         /// <param name="baseValue">The value.</param>
-        protected virtual double OnCoerceMaximum(double baseValue)
+        protected virtual decimal OnCoerceMaximum(decimal baseValue)
         {
             return Math.Max(baseValue, Minimum);
         }
@@ -519,7 +555,7 @@ namespace Avalonia.Controls
         /// Called when the <see cref="Minimum"/> property has to be coerced.
         /// </summary>
         /// <param name="baseValue">The value.</param>
-        protected virtual double OnCoerceMinimum(double baseValue)
+        protected virtual decimal OnCoerceMinimum(decimal baseValue)
         {
             return Math.Min(baseValue, Maximum);
         }
@@ -528,7 +564,7 @@ namespace Avalonia.Controls
         /// Called when the <see cref="Value"/> property has to be coerced.
         /// </summary>
         /// <param name="baseValue">The value.</param>
-        protected virtual double OnCoerceValue(double baseValue)
+        protected virtual decimal OnCoerceValue(decimal baseValue)
         {
             return baseValue;
         }
@@ -562,7 +598,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="oldValue">The old value.</param>
         /// <param name="newValue">The new value.</param>
-        protected virtual void RaiseValueChangedEvent(double oldValue, double newValue)
+        protected virtual void RaiseValueChangedEvent(decimal oldValue, decimal newValue)
         {
             var e = new NumericUpDownValueChangedEventArgs(ValueChangedEvent, oldValue, newValue);
             RaiseEvent(e);
@@ -571,9 +607,9 @@ namespace Avalonia.Controls
         /// <summary>
         /// Converts the formatted text to a value.
         /// </summary>
-        private double ConvertTextToValue(string text)
+        private decimal ConvertTextToValue(string text)
         {
-            double result = 0;
+            decimal result = 0;
 
             if (string.IsNullOrEmpty(text))
             {
@@ -609,10 +645,10 @@ namespace Avalonia.Controls
             //Manage FormatString of type "{}{0:N2} °" (in xaml) or "{0:N2} °" in code-behind.
             if (FormatString.Contains("{0"))
             {
-                return string.Format(CultureInfo, FormatString, Value);
+                return string.Format(NumberFormat, FormatString, Value);
             }
 
-            return Value.ToString(FormatString, CultureInfo);
+            return Value.ToString(FormatString, NumberFormat);
         }
 
         /// <summary>
@@ -674,6 +710,20 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Called when the <see cref="NumberFormat"/> property value changed.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void OnNumberFormatChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Sender is NumericUpDown upDown)
+            {
+                var oldValue = (NumberFormatInfo)e.OldValue;
+                var newValue = (NumberFormatInfo)e.NewValue;
+                upDown.OnNumberFormatChanged(oldValue, newValue);
+            }
+        }
+
         /// <summary>
         /// Called when the <see cref="Increment"/> property value changed.
         /// </summary>
@@ -682,8 +732,8 @@ namespace Avalonia.Controls
         {
             if (e.Sender is NumericUpDown upDown)
             {
-                var oldValue = (double)e.OldValue;
-                var newValue = (double)e.NewValue;
+                var oldValue = (decimal)e.OldValue;
+                var newValue = (decimal)e.NewValue;
                 upDown.OnIncrementChanged(oldValue, newValue);
             }
         }
@@ -724,8 +774,8 @@ namespace Avalonia.Controls
         {
             if (e.Sender is NumericUpDown upDown)
             {
-                var oldValue = (double)e.OldValue;
-                var newValue = (double)e.NewValue;
+                var oldValue = (decimal)e.OldValue;
+                var newValue = (decimal)e.NewValue;
                 upDown.OnMaximumChanged(oldValue, newValue);
             }
         }
@@ -738,8 +788,8 @@ namespace Avalonia.Controls
         {
             if (e.Sender is NumericUpDown upDown)
             {
-                var oldValue = (double)e.OldValue;
-                var newValue = (double)e.NewValue;
+                var oldValue = (decimal)e.OldValue;
+                var newValue = (decimal)e.NewValue;
                 upDown.OnMinimumChanged(oldValue, newValue);
             }
         }
@@ -766,13 +816,13 @@ namespace Avalonia.Controls
         {
             if (e.Sender is NumericUpDown upDown)
             {
-                var oldValue = (double)e.OldValue;
-                var newValue = (double)e.NewValue;
+                var oldValue = (decimal)e.OldValue;
+                var newValue = (decimal)e.NewValue;
                 upDown.OnValueChanged(oldValue, newValue);
             }
         }
 
-        private void SetValueInternal(double value)
+        private void SetValueInternal(decimal value)
         {
             _internalValueSet = true;
             try
@@ -785,7 +835,7 @@ namespace Avalonia.Controls
             }
         }
 
-        private static double OnCoerceMaximum(IAvaloniaObject instance, double value)
+        private static decimal OnCoerceMaximum(IAvaloniaObject instance, decimal value)
         {
             if (instance is NumericUpDown upDown)
             {
@@ -795,7 +845,7 @@ namespace Avalonia.Controls
             return value;
         }
 
-        private static double OnCoerceMinimum(IAvaloniaObject instance, double value)
+        private static decimal OnCoerceMinimum(IAvaloniaObject instance, decimal value)
         {
             if (instance is NumericUpDown upDown)
             {
@@ -805,7 +855,7 @@ namespace Avalonia.Controls
             return value;
         }
 
-        private static double OnCoerceIncrement(IAvaloniaObject instance, double value)
+        private static decimal OnCoerceIncrement(IAvaloniaObject instance, decimal value)
         {
             if (instance is NumericUpDown upDown)
             {
@@ -977,23 +1027,23 @@ namespace Avalonia.Controls
             return parsedTextIsValid;
         }
 
-        private double ConvertTextToValueCore(string currentValueText, string text)
+        private decimal ConvertTextToValueCore(string currentValueText, string text)
         {
-            double result;
+            decimal result;
 
             if (IsPercent(FormatString))
             {
-                result = decimal.ToDouble(ParsePercent(text, CultureInfo));
+                result = ParsePercent(text, NumberFormat);
             }
             else
             {
                 // Problem while converting new text
-                if (!double.TryParse(text, ParsingNumberStyle, CultureInfo, out var outputValue))
+                if (!decimal.TryParse(text, ParsingNumberStyle, NumberFormat, out var outputValue))
                 {
                     var shouldThrow = true;
 
                     // Check if CurrentValueText is also failing => it also contains special characters. ex : 90°
-                    if (!double.TryParse(currentValueText, ParsingNumberStyle, CultureInfo, out var _))
+                    if (!decimal.TryParse(currentValueText, ParsingNumberStyle, NumberFormat, out var _))
                     {
                         // extract non-digit characters
                         var currentValueTextSpecialCharacters = currentValueText.Where(c => !char.IsDigit(c));
@@ -1006,7 +1056,7 @@ namespace Avalonia.Controls
                                 text = text.Replace(character.ToString(), string.Empty);
                             }
                             // if without the special characters, parsing is good, do not throw
-                            if (double.TryParse(text, ParsingNumberStyle, CultureInfo, out outputValue))
+                            if (decimal.TryParse(text, ParsingNumberStyle, NumberFormat, out outputValue))
                             {
                                 shouldThrow = false;
                             }
@@ -1023,7 +1073,7 @@ namespace Avalonia.Controls
             return result;
         }
 
-        private void ValidateMinMax(double value)
+        private void ValidateMinMax(decimal value)
         {
             if (value < Minimum)
             {

src/Avalonia.Controls/NumericUpDown/NumericUpDownValueChangedEventArgs.cs

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

src/Avalonia.Controls/Platform/IPlatformLifetimeEventsImpl.cs

@@ -0,0 +1,16 @@
+using System;
+using System.ComponentModel;
+
+namespace Avalonia.Platform
+{
+    public interface IPlatformLifetimeEventsImpl
+    {
+        /// <summary>
+        /// Raised by the platform when a shutdown is requested.
+        /// </summary>
+        /// <remarks>
+        /// Raised on on OSX via the Quit menu or right-clicking on the application icon and selecting Quit.
+        /// </remarks>
+        event EventHandler<CancelEventArgs> ShutdownRequested;
+    }
+}

src/Avalonia.Controls/Platform/ITopLevelImpl.cs

@@ -22,6 +22,11 @@ namespace Avalonia.Platform
         /// </summary>
         Size ClientSize { get; }
 
+        /// <summary>
+        /// Gets the total size of the toplevel, excluding shadows.
+        /// </summary>
+        Size? FrameSize { get; }
+
         /// <summary>
         /// Gets the scaling factor for the toplevel. This is used for rendering.
         /// </summary>

src/Avalonia.Controls/Presenters/CarouselPresenter.cs

@@ -186,7 +186,7 @@ namespace Avalonia.Controls.Presenters
 
                 if (PageTransition != null && (from != null || to != null))
                 {
-                    await PageTransition.Start((Visual)from, (Visual)to, fromIndex < toIndex);
+                    await PageTransition.Start((Visual)from, (Visual)to, fromIndex < toIndex, default);
                 }
                 else if (to != null)
                 {

src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs

@@ -511,8 +511,8 @@ namespace Avalonia.Controls.Presenters
             else if (scrollable.IsLogicalScrollEnabled)
             {
                 Viewport = scrollable.Viewport;
-                Extent = scrollable.Extent;
                 Offset = scrollable.Offset;
+                Extent = scrollable.Extent;
             }
         }
 

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -6,6 +6,7 @@ using Avalonia.Metadata;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
 using Avalonia.Layout;
+using Avalonia.Media.Immutable;
 
 namespace Avalonia.Controls.Presenters
 {
@@ -360,32 +361,31 @@ namespace Avalonia.Controls.Presenters
 
             RenderInternal(context);
 
-            if (selectionStart == selectionEnd)
+            if (selectionStart == selectionEnd && _caretBlink)
             {
-                var caretBrush = CaretBrush;
+                var caretBrush = CaretBrush?.ToImmutable();
 
                 if (caretBrush is null)
                 {
-                    var backgroundColor = (Background as SolidColorBrush)?.Color;
+                    var backgroundColor = (Background as ISolidColorBrush)?.Color;
                     if (backgroundColor.HasValue)
                     {
                         byte red = (byte)~(backgroundColor.Value.R);
                         byte green = (byte)~(backgroundColor.Value.G);
                         byte blue = (byte)~(backgroundColor.Value.B);
 
-                        caretBrush = new SolidColorBrush(Color.FromRgb(red, green, blue));
+                        caretBrush = new ImmutableSolidColorBrush(Color.FromRgb(red, green, blue));
                     }
                     else
+                    {
                         caretBrush = Brushes.Black;
+                    }
                 }
 
-                if (_caretBlink)
-                {
-                    var (p1, p2) = GetCaretPoints();
-                    context.DrawLine(
-                        new Pen(caretBrush, 1),
-                        p1, p2);
-                }
+                var (p1, p2) = GetCaretPoints();
+                context.DrawLine(
+                    new ImmutablePen(caretBrush, 1),
+                    p1, p2);
             }
         }
 

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -1,18 +1,33 @@
 using System;
 using System.Collections.Specialized;
-using System.Linq;
 using Avalonia.Media;
 using Avalonia.Rendering;
-using Avalonia.Utilities;
 using Avalonia.VisualTree;
 
+#nullable enable
+
 namespace Avalonia.Controls.Primitives
 {
-    // TODO: Need to track position of adorned elements and move the adorner if they move.
+    /// <summary>
+    /// Represents a surface for showing adorners.
+    /// Adorners are always on top of the adorned element and are positioned to stay relative to the adorned element.
+    /// </summary>
+    /// <remarks>
+    /// TODO: Need to track position of adorned elements and move the adorner if they move.
+    /// </remarks>
     public class AdornerLayer : Canvas, ICustomSimpleHitTest
     {
-        public static readonly AttachedProperty<Visual> AdornedElementProperty =
-            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, Visual>("AdornedElement");
+        /// <summary>
+        /// Allows for getting and setting of the adorned element.
+        /// </summary>
+        public static readonly AttachedProperty<Visual?> AdornedElementProperty =
+            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, Visual?>("AdornedElement");
+
+        /// <summary>
+        /// Allows for controlling clipping of the adorner.
+        /// </summary>
+        public static readonly AttachedProperty<bool> IsClipEnabledProperty =
+            AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, bool>("IsClipEnabled", true);
 
         private static readonly AttachedProperty<AdornedElementInfo> s_adornedElementInfoProperty =
             AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, AdornedElementInfo>("AdornedElementInfo");
@@ -27,7 +42,7 @@ namespace Avalonia.Controls.Primitives
             Children.CollectionChanged += ChildrenCollectionChanged;
         }
 
-        public static Visual GetAdornedElement(Visual adorner)
+        public static Visual? GetAdornedElement(Visual adorner)
         {
             return adorner.GetValue(AdornedElementProperty);
         }
@@ -37,27 +52,52 @@ namespace Avalonia.Controls.Primitives
             adorner.SetValue(AdornedElementProperty, adorned);
         }
 
-        public static AdornerLayer GetAdornerLayer(IVisual visual)
+        public static AdornerLayer? GetAdornerLayer(IVisual visual)
         {
-            return visual.GetVisualAncestors()
-                .OfType<VisualLayerManager>()
-                .FirstOrDefault()
-                ?.AdornerLayer;
+            return visual.FindAncestorOfType<VisualLayerManager>()?.AdornerLayer;
         }
 
-        protected override Size ArrangeOverride(Size finalSize)
+        public static bool GetIsClipEnabled(Visual adorner)
         {
-            var parent = Parent;
+            return adorner.GetValue(IsClipEnabledProperty);
+        }
 
+        public static void SetIsClipEnabled(Visual adorner, bool isClipEnabled)
+        {
+            adorner.SetValue(IsClipEnabledProperty, isClipEnabled);
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
             foreach (var child in Children)
             {
                 var info = child.GetValue(s_adornedElementInfoProperty);
 
+                if (info != null && info.Bounds.HasValue)
+                {
+                    child.Measure(info.Bounds.Value.Bounds.Size);
+                }
+                else
+                {
+                    child.Measure(availableSize);
+                }
+            }
+
+            return default;
+        }
+
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            foreach (var child in Children)
+            {
+                var info = child.GetValue(s_adornedElementInfoProperty);
+                var isClipEnabled = child.GetValue(IsClipEnabledProperty);
+
                 if (info != null && info.Bounds.HasValue)
                 {
                     child.RenderTransform = new MatrixTransform(info.Bounds.Value.Transform);
                     child.RenderTransformOrigin = new RelativePoint(new Point(0,0), RelativeUnit.Absolute);
-                    UpdateClip(child, info.Bounds.Value);
+                    UpdateClip(child, info.Bounds.Value, isClipEnabled);
                     child.Arrange(info.Bounds.Value.Bounds);
                 }
                 else
@@ -69,16 +109,23 @@ namespace Avalonia.Controls.Primitives
             return finalSize;
         }
 
-        private static void AdornedElementChanged(AvaloniaPropertyChangedEventArgs e)
+        private static void AdornedElementChanged(AvaloniaPropertyChangedEventArgs<Visual?> e)
         {
             var adorner = (Visual)e.Sender;
-            var adorned = (Visual)e.NewValue;
+            var adorned = e.NewValue.GetValueOrDefault();
             var layer = adorner.GetVisualParent<AdornerLayer>();
             layer?.UpdateAdornedElement(adorner, adorned);
         }
 
-        private void UpdateClip(IControl control, TransformedBounds bounds)
+        private void UpdateClip(IControl control, TransformedBounds bounds, bool isEnabled)
         {
+            if (!isEnabled)
+            {
+                control.Clip = null;
+
+                return;
+            }
+
             if (!(control.Clip is RectangleGeometry clip))
             {
                 clip = new RectangleGeometry();
@@ -111,13 +158,13 @@ namespace Avalonia.Controls.Primitives
             InvalidateArrange();
         }
 
-        private void UpdateAdornedElement(Visual adorner, Visual adorned)
+        private void UpdateAdornedElement(Visual adorner, Visual? adorned)
         {
             var info = adorner.GetValue(s_adornedElementInfoProperty);
 
             if (info != null)
             {
-                info.Subscription.Dispose();
+                info.Subscription!.Dispose();
 
                 if (adorned == null)
                 {
@@ -145,7 +192,7 @@ namespace Avalonia.Controls.Primitives
 
         private class AdornedElementInfo
         {
-            public IDisposable Subscription { get; set; }
+            public IDisposable? Subscription { get; set; }
 
             public TransformedBounds? Bounds { get; set; }
         }

src/Avalonia.Controls/Primitives/LightDismissOverlayLayer.cs

@@ -52,8 +52,7 @@ namespace Avalonia.Controls.Primitives
         {
             if (InputPassThroughElement is object)
             {
-                var p = point.Transform(this.TransformToVisual(VisualRoot)!.Value);
-                var hit = VisualRoot.GetVisualAt(p, x => x != this);
+                var hit = VisualRoot.GetVisualAt(point, x => x != this);
 
                 if (hit is object)
                 {

src/Avalonia.Controls/Primitives/Popup.cs

@@ -1,4 +1,5 @@
 using System;
+using System.ComponentModel;
 using System.Linq;
 using System.Reactive.Disposables;
 using Avalonia.Controls.Presenters;
@@ -154,6 +155,8 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         public event EventHandler? Opened;
 
+        internal event EventHandler<CancelEventArgs>? Closing;
+
         public IPopupHost? Host => _openState?.PopupHost;
 
         public bool WindowManagerAddShadowHint
@@ -567,6 +570,13 @@ namespace Avalonia.Controls.Primitives
 
         private void CloseCore()
         {
+            var closingArgs = new CancelEventArgs();
+            Closing?.Invoke(this, closingArgs);
+            if (closingArgs.Cancel)
+            {
+                return;
+            }
+
             _isOpenRequested = false;
             if (_openState is null)
             {

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -10,6 +10,7 @@ using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
+using Avalonia.Threading;
 using Avalonia.VisualTree;
 
 #nullable enable
@@ -91,6 +92,12 @@ namespace Avalonia.Controls.Primitives
             AvaloniaProperty.Register<SelectingItemsControl, SelectionMode>(
                 nameof(SelectionMode));
 
+        /// <summary>
+        /// Defines the <see cref="IsTextSearchEnabled"/> property.
+        /// </summary>
+        public static readonly StyledProperty<bool> IsTextSearchEnabledProperty =
+            AvaloniaProperty.Register<ItemsControl, bool>(nameof(IsTextSearchEnabled), false);
+
         /// <summary>
         /// Event that should be raised by items that implement <see cref="ISelectable"/> to
         /// notify the parent <see cref="SelectingItemsControl"/> that their selection state
@@ -110,6 +117,8 @@ namespace Avalonia.Controls.Primitives
                 RoutingStrategies.Bubble);
 
         private static readonly IList Empty = Array.Empty<object>();
+        private string _textSearchTerm = string.Empty;
+        private DispatcherTimer? _textSearchTimer;
         private ISelectionModel? _selection;
         private int _oldSelectedIndex;
         private object? _oldSelectedItem;
@@ -305,6 +314,15 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
+        /// <summary>
+        /// Gets or sets a value that specifies whether a user can jump to a value by typing.
+        /// </summary>
+        public bool IsTextSearchEnabled
+        {
+            get { return GetValue(IsTextSearchEnabledProperty); }
+            set { SetValue(IsTextSearchEnabledProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets the selection mode.
         /// </summary>
@@ -490,6 +508,36 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
+        protected override void OnTextInput(TextInputEventArgs e)
+        {
+            if (!e.Handled)
+            {
+                if (!IsTextSearchEnabled)
+                    return;
+
+                StopTextSearchTimer();
+
+                _textSearchTerm += e.Text;
+
+                bool match(ItemContainerInfo info) =>
+                    info.ContainerControl is IContentControl control &&
+                    control.Content?.ToString()?.StartsWith(_textSearchTerm, StringComparison.OrdinalIgnoreCase) == true;
+
+                var info = ItemContainerGenerator.Containers.FirstOrDefault(match);
+
+                if (info != null)
+                {
+                    SelectedIndex = info.Index;
+                }
+
+                StartTextSearchTimer();
+
+                e.Handled = true;
+            }
+
+            base.OnTextInput(e);
+        }
+
         protected override void OnKeyDown(KeyEventArgs e)
         {
             base.OnKeyDown(e);
@@ -962,6 +1010,32 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
+        private void StartTextSearchTimer()
+        {
+            _textSearchTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
+            _textSearchTimer.Tick += TextSearchTimer_Tick;
+            _textSearchTimer.Start();
+        }
+
+        private void StopTextSearchTimer()
+        {
+            if (_textSearchTimer == null)
+            {
+                return;
+            }
+
+            _textSearchTimer.Tick -= TextSearchTimer_Tick;
+            _textSearchTimer.Stop();
+
+            _textSearchTimer = null;
+        }
+
+        private void TextSearchTimer_Tick(object sender, EventArgs e)
+        {
+            _textSearchTerm = string.Empty;
+            StopTextSearchTimer();
+        }
+
         // When in a BeginInit..EndInit block, or when the DataContext is updating, we need to
         // defer changes to the selection model because we have no idea in which order properties
         // will be set. Consider:

src/Avalonia.Controls/Primitives/Thumb.cs

@@ -56,6 +56,26 @@ namespace Avalonia.Controls.Primitives
         {
         }
 
+        protected override void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
+        {
+            if (_lastPoint.HasValue)
+            {
+                var ev = new VectorEventArgs
+                {
+                    RoutedEvent = DragCompletedEvent,
+                    Vector = _lastPoint.Value,
+                };
+
+                _lastPoint = null;
+
+                RaiseEvent(ev);
+            }
+
+            PseudoClasses.Remove(":pressed");
+
+            base.OnPointerCaptureLost(e);
+        }
+
         protected override void OnPointerMoved(PointerEventArgs e)
         {
             if (_lastPoint.HasValue)

src/Avalonia.Controls/Remote/RemoteWidget.cs

@@ -70,7 +70,7 @@ namespace Avalonia.Controls.Remote
 
         public override void Render(DrawingContext context)
         {
-            if (_lastFrame != null)
+            if (_lastFrame != null && _lastFrame.Width != 0 && _lastFrame.Height != 0)
             {
                 var fmt = (PixelFormat) _lastFrame.Format;
                 if (_bitmap == null || _bitmap.PixelSize.Width != _lastFrame.Width ||

src/Avalonia.Controls/Repeater/ViewportManager.cs

@@ -27,7 +27,6 @@ namespace Avalonia.Controls
         private IScrollAnchorProvider _scroller;
         private IControl _makeAnchorElement;
         private bool _isAnchorOutsideRealizedRange;
-        private Task _cacheBuildAction;
         private Rect _visibleWindow;
         private Rect _layoutExtent;
         // This is the expected shift by the layout.

src/Avalonia.Controls/Repeater/VirtualizationInfo.cs

@@ -27,7 +27,6 @@ namespace Avalonia.Controls
     internal class VirtualizationInfo
     {
         private int _pinCounter;
-        private object _data;
 
         public Rect ArrangeBounds { get; set; }
         public bool AutoRecycleCandidate { get; set; }

src/Avalonia.Controls/RowDefinitions.cs

@@ -1,5 +1,4 @@
 using System.Linq;
-using Avalonia.Collections;
 
 namespace Avalonia.Controls
 {
@@ -25,6 +24,11 @@ namespace Avalonia.Controls
             AddRange(GridLength.ParseLengths(s).Select(x => new RowDefinition(x)));
         }
 
+        public override string ToString()
+        {
+            return string.Join(",", this.Select(x => x.Height));
+        }
+
         /// <summary>
         /// Parses a string representation of row definitions collection.
         /// </summary>
@@ -32,4 +36,4 @@ namespace Avalonia.Controls
         /// <returns>The <see cref="RowDefinitions"/>.</returns>
         public static RowDefinitions Parse(string s) => new RowDefinitions(s);
     }
-}
+}

src/Avalonia.Controls/ScrollViewer.cs

@@ -176,8 +176,10 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="AllowAutoHide"/> property.
         /// </summary>
-        public static readonly StyledProperty<bool> AllowAutoHideProperty =
-            ScrollBar.AllowAutoHideProperty.AddOwner<ScrollViewer>();
+        public static readonly AttachedProperty<bool> AllowAutoHideProperty =
+            AvaloniaProperty.RegisterAttached<ScrollViewer, Control, bool>(
+                nameof(AllowAutoHide),
+                true);
 
         /// <summary>
         /// Defines the <see cref="ScrollChanged"/> event.
@@ -207,8 +209,8 @@ namespace Avalonia.Controls
         /// </summary>
         static ScrollViewer()
         {
-            HorizontalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>((x, e) => x.ScrollBarVisibilityChanged(e));
-            VerticalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>((x, e) => x.ScrollBarVisibilityChanged(e));
+            HorizontalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer, ScrollBarVisibility>((x, e) => x.ScrollBarVisibilityChanged(e));
+            VerticalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer, ScrollBarVisibility>((x, e) => x.ScrollBarVisibilityChanged(e));
         }
 
         /// <summary>
@@ -526,6 +528,26 @@ namespace Avalonia.Controls
             return control.GetValue(VerticalScrollBarVisibilityProperty);
         }
 
+        /// <summary>
+        /// Gets the value of the AllowAutoHideProperty attached property.
+        /// </summary>
+        /// <param name="control">The control to set the value on.</param>
+        /// <param name="value">The value of the property.</param>
+        public static void SetAllowAutoHide(Control control, bool value)
+        {
+            control.SetValue(AllowAutoHideProperty, value);
+        }
+
+        /// <summary>
+        /// Gets the value of the AllowAutoHideProperty attached property.
+        /// </summary>
+        /// <param name="control">The control to read the value from.</param>
+        /// <returns>The value of the property.</returns>
+        public static bool GetAllowAutoHide(Control control)
+        {
+            return control.GetValue(AllowAutoHideProperty);
+        }
+
         /// <summary>
         /// Gets the value of the VerticalScrollBarVisibility attached property.
         /// </summary>
@@ -604,10 +626,10 @@ namespace Avalonia.Controls
             CalculatedPropertiesChanged();
         }
 
-        private void ScrollBarVisibilityChanged(AvaloniaPropertyChangedEventArgs e)
+        private void ScrollBarVisibilityChanged(AvaloniaPropertyChangedEventArgs<ScrollBarVisibility> e)
         {
-            var wasEnabled = !ScrollBarVisibility.Disabled.Equals(e.OldValue);
-            var isEnabled = !ScrollBarVisibility.Disabled.Equals(e.NewValue);
+            var wasEnabled = e.OldValue.GetValueOrDefault() != ScrollBarVisibility.Disabled;
+            var isEnabled = e.NewValue.GetValueOrDefault() != ScrollBarVisibility.Disabled;
 
             if (wasEnabled != isEnabled)
             {

src/Avalonia.Controls/Shapes/Arc.cs

@@ -0,0 +1,103 @@
+using System;
+using Avalonia.Media;
+
+namespace Avalonia.Controls.Shapes
+{
+    public class Arc : Shape
+    {
+        /// <summary>
+        /// Defines the <see cref="StartAngle"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> StartAngleProperty =
+            AvaloniaProperty.Register<Arc, double>(nameof(StartAngle), 0.0);
+
+        /// <summary>
+        /// Defines the <see cref="SweepAngle"/> property.
+        /// </summary>
+        public static readonly StyledProperty<double> SweepAngleProperty =
+            AvaloniaProperty.Register<Arc, double>(nameof(SweepAngle), 0.0);
+
+        static Arc()
+        {
+            StrokeThicknessProperty.OverrideDefaultValue<Arc>(1);
+            AffectsGeometry<Arc>(BoundsProperty, StrokeThicknessProperty, StartAngleProperty, SweepAngleProperty);
+        }
+
+        /// <summary>
+        /// Gets or sets the angle at which the arc starts, in degrees.
+        /// </summary>
+        public double StartAngle
+        {
+            get => GetValue(StartAngleProperty);
+            set => SetValue(StartAngleProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the angle, in degrees, added to the <see cref="StartAngle"/> defining where the arc ends.
+        /// A positive value is clockwise, negative is counter-clockwise.
+        /// </summary>
+        public double SweepAngle
+        {
+            get => GetValue(SweepAngleProperty);
+            set => SetValue(SweepAngleProperty, value);
+        }
+
+        protected override Geometry CreateDefiningGeometry()
+        {
+            var angle1 = DegreesToRad(StartAngle);
+            var angle2 = angle1 + DegreesToRad(SweepAngle);
+
+            var startAngle = Math.Min(angle1, angle2);
+            var sweepAngle = Math.Max(angle1, angle2);
+
+            var normStart = RadToNormRad(startAngle);
+            var normEnd = RadToNormRad(sweepAngle);
+
+            var rect = new Rect(Bounds.Size);
+
+            if ((normStart == normEnd) && (startAngle != sweepAngle)) // Complete ring.
+            {
+                return new EllipseGeometry(rect.Deflate(StrokeThickness / 2));
+            }
+            else if (SweepAngle == 0)
+            {
+                return new StreamGeometry();
+            }
+            else // Partial arc.
+            {
+                var deflatedRect = rect.Deflate(StrokeThickness / 2);
+
+                var centerX = rect.Center.X;
+                var centerY = rect.Center.Y;
+
+                var radiusX = deflatedRect.Width / 2;
+                var radiusY = deflatedRect.Height / 2;
+
+                var angleGap = RadToNormRad(sweepAngle - startAngle);
+
+                var startPoint = GetRingPoint(radiusX, radiusY, centerX, centerY, startAngle);
+                var endPoint = GetRingPoint(radiusX, radiusY, centerX, centerY, sweepAngle);
+
+                var arcGeometry = new StreamGeometry();
+
+                using (var ctx = arcGeometry.Open())
+                {
+                    ctx.BeginFigure(startPoint, false);
+                    ctx.ArcTo(endPoint, new Size(radiusX, radiusY), angleGap, angleGap >= Math.PI,
+                        SweepDirection.Clockwise);
+                    ctx.EndFigure(false);
+                }
+
+                return arcGeometry;
+            }
+        }
+
+        static double DegreesToRad(double inAngle) =>
+            inAngle * Math.PI / 180;
+
+        static double RadToNormRad(double inAngle) => ((inAngle % (Math.PI * 2)) + (Math.PI * 2)) % (Math.PI * 2);
+
+        static Point GetRingPoint(double radiusX, double radiusY, double centerX, double centerY, double angle) =>
+            new Point((radiusX * Math.Cos(angle)) + centerX, (radiusY * Math.Sin(angle)) + centerY);
+    }
+}

src/Avalonia.Controls/Shapes/Shape.cs

@@ -1,6 +1,7 @@
 using System;
 using Avalonia.Collections;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 
 #nullable enable
 
@@ -199,8 +200,29 @@ namespace Avalonia.Controls.Shapes
 
             if (geometry != null)
             {
-                var pen = new Pen(Stroke, StrokeThickness, new DashStyle(StrokeDashArray, StrokeDashOffset),
-                     StrokeLineCap, StrokeJoin);
+                var stroke = Stroke;
+
+                ImmutablePen? pen = null;
+
+                if (stroke != null)
+                {
+                    var strokeDashArray = StrokeDashArray;
+
+                    ImmutableDashStyle? dashStyle = null;
+
+                    if (strokeDashArray != null && strokeDashArray.Count > 0)
+                    {
+                        dashStyle = new ImmutableDashStyle(strokeDashArray, StrokeDashOffset);
+                    }
+
+                    pen = new ImmutablePen(
+                        stroke.ToImmutable(),
+                        StrokeThickness,
+                        dashStyle,
+                        StrokeLineCap,
+                        StrokeJoin);
+                }
+
                 context.DrawGeometry(Fill, pen, geometry);
             }
         }

src/Avalonia.Controls/SplitView.cs

@@ -133,7 +133,7 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<SplitView, object?>(nameof(Pane));
 
         /// <summary>
-        /// Defines the <see cref="HeaderTemplate"/> property.
+        /// Defines the <see cref="PaneTemplate"/> property.
         /// </summary>
         public static readonly StyledProperty<IDataTemplate?> PaneTemplateProperty =
             AvaloniaProperty.Register<HeaderedContentControl, IDataTemplate?>(nameof(PaneTemplate));

src/Avalonia.Controls/TextBox.cs

@@ -119,9 +119,9 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<TextBox, bool>(nameof(RevealPassword));
         
         public static readonly DirectProperty<TextBox, bool> CanCutProperty =
-                    AvaloniaProperty.RegisterDirect<TextBox, bool>(
-                        nameof(CanCut),
-                        o => o.CanCut);
+            AvaloniaProperty.RegisterDirect<TextBox, bool>(
+                nameof(CanCut),
+                o => o.CanCut);
 
         public static readonly DirectProperty<TextBox, bool> CanCopyProperty =
             AvaloniaProperty.RegisterDirect<TextBox, bool>(
@@ -129,11 +129,23 @@ namespace Avalonia.Controls
                 o => o.CanCopy);
 
         public static readonly DirectProperty<TextBox, bool> CanPasteProperty =
-                    AvaloniaProperty.RegisterDirect<TextBox, bool>(
-                        nameof(CanPaste),
-                        o => o.CanPaste);
+            AvaloniaProperty.RegisterDirect<TextBox, bool>(
+                nameof(CanPaste),
+                o => o.CanPaste);
+
+        public static readonly StyledProperty<bool> IsUndoEnabledProperty =
+            AvaloniaProperty.Register<TextBox, bool>(
+                nameof(IsUndoEnabled), 
+                defaultValue: true);
 
-        struct UndoRedoState : IEquatable<UndoRedoState>
+        public static readonly DirectProperty<TextBox, int> UndoLimitProperty =
+            AvaloniaProperty.RegisterDirect<TextBox, int>(
+                nameof(UndoLimit),
+                o => o.UndoLimit,
+                (o, v) => o.UndoLimit = v,
+                unsetValue: -1);
+
+        readonly struct UndoRedoState : IEquatable<UndoRedoState>
         {
             public string Text { get; }
             public int CaretPosition { get; }
@@ -218,7 +230,7 @@ namespace Avalonia.Controls
                 value = CoerceCaretIndex(value);
                 SetAndRaise(CaretIndexProperty, ref _caretIndex, value);
                 UndoRedoState state;
-                if (_undoRedoHelper.TryGetLastState(out state) && state.Text == Text)
+                if (IsUndoEnabled && _undoRedoHelper.TryGetLastState(out state) && state.Text == Text)
                     _undoRedoHelper.UpdateLastState();
             }
         }
@@ -316,7 +328,7 @@ namespace Avalonia.Controls
                     SelectionEnd = CoerceCaretIndex(SelectionEnd, value);
                     CaretIndex = CoerceCaretIndex(caretIndex, value);
 
-                    if (SetAndRaise(TextProperty, ref _text, value) && !_isUndoingRedoing)
+                    if (SetAndRaise(TextProperty, ref _text, value) && IsUndoEnabled && !_isUndoingRedoing)
                     {
                         _undoRedoHelper.Clear();
                     }
@@ -329,7 +341,7 @@ namespace Avalonia.Controls
             get { return GetSelection(); }
             set
             {
-                _undoRedoHelper.Snapshot();
+                SnapshotUndoRedo();
                 if (string.IsNullOrEmpty(value))
                 {
                     DeleteSelection();
@@ -338,7 +350,7 @@ namespace Avalonia.Controls
                 {
                     HandleTextInput(value);
                 }
-                _undoRedoHelper.Snapshot();
+                SnapshotUndoRedo();
             }
         }
 
@@ -446,6 +458,36 @@ namespace Avalonia.Controls
             private set { SetAndRaise(CanPasteProperty, ref _canPaste, value); }
         }
 
+        /// <summary>
+        /// Property for determining whether undo/redo is enabled
+        /// </summary>
+        public bool IsUndoEnabled
+        {
+            get { return GetValue(IsUndoEnabledProperty); }
+            set { SetValue(IsUndoEnabledProperty, value); }
+        }
+
+        public int UndoLimit
+        {
+            get { return _undoRedoHelper.Limit; }
+            set
+            {
+                if (_undoRedoHelper.Limit != value)
+                {
+                    // can't use SetAndRaise due to using _undoRedoHelper.Limit
+                    // (can't send a ref of a property to SetAndRaise),
+                    // so use RaisePropertyChanged instead.
+                    var oldValue = _undoRedoHelper.Limit;
+                    _undoRedoHelper.Limit = value;
+                    RaisePropertyChanged(UndoLimitProperty, oldValue, value);
+                } 
+                // from docs at
+                // https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.primitives.textboxbase.isundoenabled:
+                // "Setting UndoLimit clears the undo queue."
+                _undoRedoHelper.Clear();
+            }
+        }
+
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
             _presenter = e.NameScope.Get<TextPresenter>("PART_TextPresenter");
@@ -465,6 +507,15 @@ namespace Avalonia.Controls
                 UpdatePseudoclasses();
                 UpdateCommandStates();
             }
+            else if (change.Property == IsUndoEnabledProperty && change.NewValue.GetValueOrDefault<bool>() == false)
+            {
+                // from docs at
+                // https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.primitives.textboxbase.isundoenabled:
+                // "Setting this property to false clears the undo stack.
+                // Therefore, if you disable undo and then re-enable it, undo commands still do not work
+                // because the undo stack was emptied when you disabled undo."
+                _undoRedoHelper.Clear();
+            }
         }
 
         private void UpdateCommandStates()
@@ -551,7 +602,10 @@ namespace Avalonia.Controls
                 SetTextInternal(text.Substring(0, caretIndex) + input + text.Substring(caretIndex));
                 CaretIndex += input.Length;
                 ClearSelection();
-                _undoRedoHelper.DiscardRedo();
+                if (IsUndoEnabled)
+                {
+                    _undoRedoHelper.DiscardRedo();
+                }
             }
         }
 
@@ -570,10 +624,10 @@ namespace Avalonia.Controls
             var text = GetSelection();
             if (text is null) return;
 
-            _undoRedoHelper.Snapshot();
+            SnapshotUndoRedo();
             Copy();
             DeleteSelection();
-            _undoRedoHelper.Snapshot();
+            SnapshotUndoRedo();
         }
 
         public async void Copy()
@@ -591,9 +645,9 @@ namespace Avalonia.Controls
 
             if (text is null) return;
 
-            _undoRedoHelper.Snapshot();
+            SnapshotUndoRedo();
             HandleTextInput(text);
-            _undoRedoHelper.Snapshot();
+            SnapshotUndoRedo();
         }
 
         protected override void OnKeyDown(KeyEventArgs e)
@@ -638,7 +692,7 @@ namespace Avalonia.Controls
                 Paste();
                 handled = true;
             }
-            else if (Match(keymap.Undo))
+            else if (Match(keymap.Undo) && IsUndoEnabled)
             {
                 try
                 {
@@ -652,7 +706,7 @@ namespace Avalonia.Controls
 
                 handled = true;
             }
-            else if (Match(keymap.Redo))
+            else if (Match(keymap.Redo) && IsUndoEnabled)
             {
                 try
                 {
@@ -752,7 +806,7 @@ namespace Avalonia.Controls
                         break;
 
                     case Key.Back:
-                        _undoRedoHelper.Snapshot();
+                        SnapshotUndoRedo();
                         if (hasWholeWordModifiers && SelectionStart == SelectionEnd)
                         {
                             SetSelectionForControlBackspace();
@@ -776,13 +830,13 @@ namespace Avalonia.Controls
                             CaretIndex -= removedCharacters;
                             ClearSelection();
                         }
-                        _undoRedoHelper.Snapshot();
+                        SnapshotUndoRedo();
 
                         handled = true;
                         break;
 
                     case Key.Delete:
-                        _undoRedoHelper.Snapshot();
+                        SnapshotUndoRedo();
                         if (hasWholeWordModifiers && SelectionStart == SelectionEnd)
                         {
                             SetSelectionForControlDelete();
@@ -804,7 +858,7 @@ namespace Avalonia.Controls
                             SetTextInternal(text.Substring(0, caretIndex) +
                                             text.Substring(caretIndex + removedCharacters));
                         }
-                        _undoRedoHelper.Snapshot();
+                        SnapshotUndoRedo();
 
                         handled = true;
                         break;
@@ -812,9 +866,9 @@ namespace Avalonia.Controls
                     case Key.Enter:
                         if (AcceptsReturn)
                         {
-                            _undoRedoHelper.Snapshot();
+                            SnapshotUndoRedo();
                             HandleTextInput(NewLine);
-                            _undoRedoHelper.Snapshot();
+                            SnapshotUndoRedo();
                             handled = true;
                         }
 
@@ -823,9 +877,9 @@ namespace Avalonia.Controls
                     case Key.Tab:
                         if (AcceptsTab)
                         {
-                            _undoRedoHelper.Snapshot();
+                            SnapshotUndoRedo();
                             HandleTextInput("\t");
-                            _undoRedoHelper.Snapshot();
+                            SnapshotUndoRedo();
                             handled = true;
                         }
                         else
@@ -1044,6 +1098,11 @@ namespace Avalonia.Controls
 
         private bool MoveVertical(int count)
         {
+            if (_presenter is null)
+            {
+                return false;
+            }
+
             var formattedText = _presenter.FormattedText;
             var lines = formattedText.GetLines().ToList();
             var caretIndex = CaretIndex;
@@ -1059,14 +1118,17 @@ namespace Avalonia.Controls
                 CaretIndex = hit.TextPosition + (hit.IsTrailing ? 1 : 0);
                 return true;
             }
-            else
-            {
-                return false;
-            }
+
+            return false;
         }
 
         private void MoveHome(bool document)
         {
+            if (_presenter is null)
+            {
+                return;
+            }
+            
             var text = Text ?? string.Empty;
             var caretIndex = CaretIndex;
 
@@ -1097,6 +1159,11 @@ namespace Avalonia.Controls
 
         private void MoveEnd(bool document)
         {
+            if (_presenter is null)
+            {
+                return;
+            }
+            
             var text = Text ?? string.Empty;
             var caretIndex = CaretIndex;
 
@@ -1236,7 +1303,7 @@ namespace Avalonia.Controls
 
         private void UpdatePseudoclasses()
         {
-            PseudoClasses.Set(":empty", string.IsNullOrWhiteSpace(Text));
+            PseudoClasses.Set(":empty", string.IsNullOrEmpty(Text));
         }
 
         private bool IsPasswordBox => PasswordChar != default(char);
@@ -1251,5 +1318,13 @@ namespace Avalonia.Controls
                 ClearSelection();
             }
         }
+
+        private void SnapshotUndoRedo()
+        {
+            if (IsUndoEnabled)
+            {
+                _undoRedoHelper.Snapshot();
+            }
+        }
     }
 }

src/Avalonia.Controls/TickBar.cs

@@ -1,6 +1,7 @@
 using Avalonia.Collections;
 using Avalonia.Layout;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 using Avalonia.Utilities;
 
 namespace Avalonia.Controls
@@ -295,7 +296,7 @@ namespace Avalonia.Controls
                 endPoint = pt;
             }
 
-            var pen = new Pen(Fill, 1.0d);
+            var pen = new ImmutablePen(Fill?.ToImmutable(), 1.0d);
 
             // Is it Vertical?
             if (Placement == TickBarPlacement.Left || Placement == TickBarPlacement.Right)

src/Avalonia.Controls/TopLevel.cs

@@ -42,6 +42,12 @@ namespace Avalonia.Controls
         public static readonly DirectProperty<TopLevel, Size> ClientSizeProperty =
             AvaloniaProperty.RegisterDirect<TopLevel, Size>(nameof(ClientSize), o => o.ClientSize);
 
+        /// <summary>
+        /// Defines the <see cref="FrameSize"/> property.
+        /// </summary>
+        public static readonly DirectProperty<TopLevel, Size?> FrameSizeProperty =
+            AvaloniaProperty.RegisterDirect<TopLevel, Size?>(nameof(FrameSize), o => o.FrameSize);
+
         /// <summary>
         /// Defines the <see cref="IInputRoot.PointerOverElement"/> property.
         /// </summary>
@@ -74,6 +80,7 @@ namespace Avalonia.Controls
         private readonly IPlatformRenderInterface _renderInterface;
         private readonly IGlobalStyles _globalStyles;
         private Size _clientSize;
+        private Size? _frameSize;
         private WindowTransparencyLevel _actualTransparencyLevel;
         private ILayoutManager _layoutManager;
         private Border _transparencyFallbackBorder;
@@ -162,6 +169,7 @@ namespace Avalonia.Controls
             styler?.ApplyStyles(this);
 
             ClientSize = impl.ClientSize;
+            FrameSize = impl.FrameSize;
             
             this.GetObservable(PointerOverElementProperty)
                 .Select(
@@ -198,6 +206,15 @@ namespace Avalonia.Controls
             protected set { SetAndRaise(ClientSizeProperty, ref _clientSize, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the total size of the window.
+        /// </summary>
+        public Size? FrameSize
+        {
+            get { return _frameSize; }
+            protected set { SetAndRaise(FrameSizeProperty, ref _frameSize, value); }
+        }
+
         /// <summary>
         /// Gets or sets the <see cref="WindowTransparencyLevel"/> that the TopLevel should use when possible.
         /// </summary>
@@ -367,6 +384,7 @@ namespace Avalonia.Controls
         protected virtual void HandleResized(Size clientSize)
         {
             ClientSize = clientSize;
+            FrameSize = PlatformImpl.FrameSize;
             Width = clientSize.Width;
             Height = clientSize.Height;
             LayoutManager.ExecuteLayoutPass();

src/Avalonia.Controls/TreeView.cs

@@ -166,11 +166,9 @@ namespace Avalonia.Controls
         {
             item.IsExpanded = true;
 
-            var panel = item.Presenter.Panel;
-
-            if (panel != null)
+            if (item.Presenter?.Panel != null)
             {
-                foreach (var child in panel.Children)
+                foreach (var child in item.Presenter.Panel.Children)
                 {
                     if (child is TreeViewItem treeViewItem)
                     {

src/Avalonia.Controls/Utils/BorderRenderHelper.cs

@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 using Avalonia.Platform;
 using Avalonia.Utilities;
 
@@ -114,9 +115,9 @@ namespace Avalonia.Controls.Utils
                 var borderThickness = _borderThickness.Top;
                 IPen pen = null;
 
-                if (borderThickness > 0)
+                if (borderBrush != null && borderThickness > 0)
                 {
-                    pen = new Pen(borderBrush, borderThickness);
+                    pen = new ImmutablePen(borderBrush.ToImmutable(), borderThickness);
                 }
 
                 var rect = new Rect(_size);

src/Avalonia.Controls/Utils/UndoRedoHelper.cs

@@ -22,6 +22,10 @@ namespace Avalonia.Controls.Utils
 
         private LinkedListNode<TState> _currentNode;
 
+        /// <summary>
+        /// Maximum number of states this helper can store for undo/redo.
+        /// If -1, no limit is imposed.
+        /// </summary>
         public int Limit { get; set; } = 10;
 
         public UndoRedoHelper(IUndoRedoHost host)
@@ -54,7 +58,10 @@ namespace Avalonia.Controls.Utils
         public bool HasState => _currentNode != null;
         public void UpdateLastState(TState state)
         {
-            _states.Last.Value = state;
+            if (_states.Last != null)
+            {
+                _states.Last.Value = state;
+            } 
         }
 
         public void UpdateLastState()
@@ -86,7 +93,7 @@ namespace Avalonia.Controls.Utils
                     DiscardRedo();
                 _states.AddLast(current);
                 _currentNode = _states.Last;
-                if (_states.Count > Limit)
+                if (Limit != -1 && _states.Count > Limit)
                     _states.RemoveFirst();
             }
         }

src/Avalonia.Controls/Window.cs

@@ -592,6 +592,14 @@ namespace Avalonia.Controls
                     owner.RemoveChild(this);
                 }
 
+                if (_children.Count > 0)
+                {
+                    foreach (var child in _children.ToArray())
+                    {
+                        child.child.Hide();
+                    }
+                }
+
                 Owner = null;
 
                 PlatformImpl?.Hide();
@@ -635,6 +643,22 @@ namespace Avalonia.Controls
                 throw new InvalidOperationException("Cannot re-show a closed window.");
             }
 
+            if (parent != null)
+            {
+                if (parent.PlatformImpl == null)
+                {
+                    throw new InvalidOperationException("Cannot show a window with a closed parent.");
+                }
+                else if (parent == this)
+                {
+                    throw new InvalidOperationException("A Window cannot be its own parent.");
+                }
+                else if (!parent.IsVisible)
+                {
+                    throw new InvalidOperationException("Cannot show window with non-visible parent.");
+                }
+            }
+
             if (IsVisible)
             {
                 return;
@@ -708,11 +732,22 @@ namespace Avalonia.Controls
             {
                 throw new ArgumentNullException(nameof(owner));
             }
-
-            if (IsVisible)
+            else if (owner.PlatformImpl == null)
+            {
+                throw new InvalidOperationException("Cannot show a window with a closed owner.");
+            }
+            else if (owner == this)
+            {
+                throw new InvalidOperationException("A Window cannot be its own owner.");
+            }
+            else if (IsVisible)
             {
                 throw new InvalidOperationException("The window is already being shown.");
             }
+            else if (!owner.IsVisible)
+            {
+                throw new InvalidOperationException("Cannot show window with non-visible parent.");
+            }
 
             RaiseEvent(new RoutedEventArgs(WindowOpenedEvent));
 

src/Avalonia.Controls/WindowBase.cs

@@ -222,6 +222,7 @@ namespace Avalonia.Controls
         protected override void HandleResized(Size clientSize)
         {
             ClientSize = clientSize;
+            FrameSize = PlatformImpl.FrameSize;
             LayoutManager.ExecuteLayoutPass();
             Renderer?.Resized(clientSize);
         }

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -21,6 +21,7 @@ namespace Avalonia.DesignerSupport.Remote
         public IPlatformHandle Handle { get; }
         public Size MaxAutoSizeHint { get; }
         public Size ClientSize { get; }
+        public Size? FrameSize => null;
         public double RenderScaling { get; } = 1.0;
         public double DesktopScaling => 1.0;
         public IEnumerable<object> Surfaces { get; }

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -3,12 +3,16 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Avalonia</RootNamespace>
     <PackageId>Avalonia.Diagnostics</PackageId>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Update="**\*.xaml.cs">
       <DependentUpon>%(Filename)</DependentUpon>
     </Compile>
   </ItemGroup>
+  <ItemGroup>
+    <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />

src/Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.axaml

@@ -27,7 +27,9 @@
             <Image>
               <DrawingImage>
                 <GeometryDrawing Brush="{Binding $parent[ToggleButton].Foreground}">
-                  M7.495 9.052L8.386 11.402H9.477L6.237 3H5.217L2 11.402H3.095L3.933 9.052H7.495ZM5.811 4.453L5.855 4.588L7.173 8.162H4.255L5.562 4.588L5.606 4.453L5.644 4.297L5.676 4.145L5.697 4.019H5.72L5.744 4.145L5.773 4.297L5.811 4.453ZM13.795 10.464V11.4H14.755V7.498C14.755 6.779 14.575 6.226 14.216 5.837C13.857 5.448 13.327 5.254 12.628 5.254C12.429 5.254 12.227 5.273 12.022 5.31C11.817 5.347 11.622 5.394 11.439 5.451C11.256 5.508 11.091 5.569 10.944 5.636C10.797 5.703 10.683 5.765 10.601 5.824V6.808C10.867 6.578 11.167 6.397 11.505 6.268C11.843 6.139 12.194 6.075 12.557 6.075C12.745 6.075 12.915 6.103 13.07 6.16C13.225 6.217 13.357 6.306 13.466 6.427C13.575 6.548 13.659 6.706 13.718 6.899C13.777 7.092 13.806 7.326 13.806 7.599L11.995 7.851C11.651 7.898 11.355 7.977 11.107 8.088C10.859 8.199 10.654 8.339 10.492 8.507C10.33 8.675 10.21 8.868 10.132 9.087C10.054 9.306 10.015 9.546 10.015 9.808C10.015 10.054 10.057 10.283 10.139 10.496C10.221 10.709 10.342 10.893 10.502 11.047C10.662 11.201 10.862 11.323 11.1 11.413C11.338 11.503 11.613 11.548 11.926 11.548C12.328 11.548 12.686 11.456 13.001 11.27C13.316 11.084 13.573 10.816 13.772 10.464H13.795ZM11.667 8.721C11.843 8.657 12.068 8.607 12.341 8.572L13.806 8.367V8.976C13.806 9.222 13.765 9.451 13.683 9.664C13.601 9.877 13.486 10.063 13.34 10.221C13.194 10.379 13.019 10.503 12.816 10.593C12.613 10.683 12.39 10.728 12.148 10.728C11.961 10.728 11.795 10.703 11.653 10.652C11.511 10.601 11.392 10.53 11.296 10.441C11.2 10.352 11.127 10.247 11.076 10.125C11.025 10.003 11 9.873 11 9.732C11 9.568 11.018 9.421 11.055 9.292C11.092 9.163 11.16 9.051 11.257 8.958C11.354 8.865 11.491 8.785 11.667 8.721Z
+                    <GeometryDrawing.Geometry>
+                    M7.495 9.052L8.386 11.402H9.477L6.237 3H5.217L2 11.402H3.095L3.933 9.052H7.495ZM5.811 4.453L5.855 4.588L7.173 8.162H4.255L5.562 4.588L5.606 4.453L5.644 4.297L5.676 4.145L5.697 4.019H5.72L5.744 4.145L5.773 4.297L5.811 4.453ZM13.795 10.464V11.4H14.755V7.498C14.755 6.779 14.575 6.226 14.216 5.837C13.857 5.448 13.327 5.254 12.628 5.254C12.429 5.254 12.227 5.273 12.022 5.31C11.817 5.347 11.622 5.394 11.439 5.451C11.256 5.508 11.091 5.569 10.944 5.636C10.797 5.703 10.683 5.765 10.601 5.824V6.808C10.867 6.578 11.167 6.397 11.505 6.268C11.843 6.139 12.194 6.075 12.557 6.075C12.745 6.075 12.915 6.103 13.07 6.16C13.225 6.217 13.357 6.306 13.466 6.427C13.575 6.548 13.659 6.706 13.718 6.899C13.777 7.092 13.806 7.326 13.806 7.599L11.995 7.851C11.651 7.898 11.355 7.977 11.107 8.088C10.859 8.199 10.654 8.339 10.492 8.507C10.33 8.675 10.21 8.868 10.132 9.087C10.054 9.306 10.015 9.546 10.015 9.808C10.015 10.054 10.057 10.283 10.139 10.496C10.221 10.709 10.342 10.893 10.502 11.047C10.662 11.201 10.862 11.323 11.1 11.413C11.338 11.503 11.613 11.548 11.926 11.548C12.328 11.548 12.686 11.456 13.001 11.27C13.316 11.084 13.573 10.816 13.772 10.464H13.795ZM11.667 8.721C11.843 8.657 12.068 8.607 12.341 8.572L13.806 8.367V8.976C13.806 9.222 13.765 9.451 13.683 9.664C13.601 9.877 13.486 10.063 13.34 10.221C13.194 10.379 13.019 10.503 12.816 10.593C12.613 10.683 12.39 10.728 12.148 10.728C11.961 10.728 11.795 10.703 11.653 10.652C11.511 10.601 11.392 10.53 11.296 10.441C11.2 10.352 11.127 10.247 11.076 10.125C11.025 10.003 11 9.873 11 9.732C11 9.568 11.018 9.421 11.055 9.292C11.092 9.163 11.16 9.051 11.257 8.958C11.354 8.865 11.491 8.785 11.667 8.721Z
+                    </GeometryDrawing.Geometry>
                 </GeometryDrawing>
               </DrawingImage>
             </Image>
@@ -38,7 +40,9 @@
             <Image>
               <DrawingImage>
                 <GeometryDrawing Brush="{Binding $parent[ToggleButton].Foreground}">
-                  M1 2H15V3H1V2ZM14 4H13V12H14V4ZM11.272 8.387C11.194 8.088 11.073 7.825 10.912 7.601C10.751 7.377 10.547 7.2 10.303 7.071C10.059 6.942 9.769 6.878 9.437 6.878C9.239 6.878 9.057 6.902 8.89 6.951C8.725 7 8.574 7.068 8.437 7.156C8.301 7.244 8.18 7.35 8.072 7.474L7.893 7.732V4.578H7V12H7.893V11.425L8.019 11.6C8.106 11.702 8.208 11.79 8.323 11.869C8.44 11.947 8.572 12.009 8.721 12.055C8.87 12.101 9.035 12.123 9.219 12.123C9.572 12.123 9.885 12.052 10.156 11.911C10.428 11.768 10.655 11.573 10.838 11.325C11.021 11.075 11.159 10.782 11.252 10.446C11.345 10.108 11.392 9.743 11.392 9.349C11.391 9.007 11.352 8.686 11.272 8.387ZM9.793 7.78C9.944 7.851 10.075 7.956 10.183 8.094C10.292 8.234 10.377 8.407 10.438 8.611C10.489 8.785 10.52 8.982 10.527 9.198L10.52 9.323C10.52 9.65 10.487 9.943 10.42 10.192C10.353 10.438 10.259 10.645 10.142 10.806C10.025 10.968 9.882 11.091 9.721 11.172C9.399 11.334 8.961 11.338 8.652 11.187C8.499 11.112 8.366 11.012 8.259 10.891C8.174 10.795 8.103 10.675 8.041 10.524C8.041 10.524 7.862 10.077 7.862 9.577C7.862 9.077 8.041 8.575 8.041 8.575C8.103 8.398 8.177 8.257 8.265 8.145C8.379 8.002 8.521 7.886 8.689 7.8C8.857 7.714 9.054 7.671 9.276 7.671C9.466 7.671 9.64 7.708 9.793 7.78ZM15 13H1V14H15V13ZM2.813 10L2.085 12.031H1L1.025 11.959L3.466 4.87305H4.407L6.892 12.031H5.81L5.032 10H2.813ZM3.934 6.42205H3.912L3.007 9.17505H4.848L3.934 6.42205Z
+                    <GeometryDrawing.Geometry>
+                    M1 2H15V3H1V2ZM14 4H13V12H14V4ZM11.272 8.387C11.194 8.088 11.073 7.825 10.912 7.601C10.751 7.377 10.547 7.2 10.303 7.071C10.059 6.942 9.769 6.878 9.437 6.878C9.239 6.878 9.057 6.902 8.89 6.951C8.725 7 8.574 7.068 8.437 7.156C8.301 7.244 8.18 7.35 8.072 7.474L7.893 7.732V4.578H7V12H7.893V11.425L8.019 11.6C8.106 11.702 8.208 11.79 8.323 11.869C8.44 11.947 8.572 12.009 8.721 12.055C8.87 12.101 9.035 12.123 9.219 12.123C9.572 12.123 9.885 12.052 10.156 11.911C10.428 11.768 10.655 11.573 10.838 11.325C11.021 11.075 11.159 10.782 11.252 10.446C11.345 10.108 11.392 9.743 11.392 9.349C11.391 9.007 11.352 8.686 11.272 8.387ZM9.793 7.78C9.944 7.851 10.075 7.956 10.183 8.094C10.292 8.234 10.377 8.407 10.438 8.611C10.489 8.785 10.52 8.982 10.527 9.198L10.52 9.323C10.52 9.65 10.487 9.943 10.42 10.192C10.353 10.438 10.259 10.645 10.142 10.806C10.025 10.968 9.882 11.091 9.721 11.172C9.399 11.334 8.961 11.338 8.652 11.187C8.499 11.112 8.366 11.012 8.259 10.891C8.174 10.795 8.103 10.675 8.041 10.524C8.041 10.524 7.862 10.077 7.862 9.577C7.862 9.077 8.041 8.575 8.041 8.575C8.103 8.398 8.177 8.257 8.265 8.145C8.379 8.002 8.521 7.886 8.689 7.8C8.857 7.714 9.054 7.671 9.276 7.671C9.466 7.671 9.64 7.708 9.793 7.78ZM15 13H1V14H15V13ZM2.813 10L2.085 12.031H1L1.025 11.959L3.466 4.87305H4.407L6.892 12.031H5.81L5.032 10H2.813ZM3.934 6.42205H3.912L3.007 9.17505H4.848L3.934 6.42205Z
+                    </GeometryDrawing.Geometry>
                 </GeometryDrawing>
               </DrawingImage>
             </Image>
@@ -49,7 +53,9 @@
             <Image>
               <DrawingImage>
                 <GeometryDrawing Brush="{Binding $parent[ToggleButton].Foreground}">
-                  M10.0122 2H10.9879V5.11346L13.5489 3.55609L14.034 4.44095L11.4702 6L14.034 7.55905L13.5489 8.44391L10.9879 6.88654V10H10.0122V6.88654L7.45114 8.44391L6.96606 7.55905L9.5299 6L6.96606 4.44095L7.45114 3.55609L10.0122 5.11346V2ZM2 10H6V14H2V10Z
+                    <GeometryDrawing.Geometry>
+                    M10.0122 2H10.9879V5.11346L13.5489 3.55609L14.034 4.44095L11.4702 6L14.034 7.55905L13.5489 8.44391L10.9879 6.88654V10H10.0122V6.88654L7.45114 8.44391L6.96606 7.55905L9.5299 6L6.96606 4.44095L7.45114 3.55609L10.0122 5.11346V2ZM2 10H6V14H2V10Z
+                    </GeometryDrawing.Geometry>
                 </GeometryDrawing>
               </DrawingImage>
             </Image>

src/Avalonia.Diagnostics/Diagnostics/Controls/ThicknessEditor.cs

@@ -10,8 +10,8 @@ namespace Avalonia.Diagnostics.Controls
             AvaloniaProperty.RegisterDirect<ThicknessEditor, Thickness>(nameof(Thickness), o => o.Thickness,
                 (o, v) => o.Thickness = v, defaultBindingMode: BindingMode.TwoWay);
 
-        public static readonly DirectProperty<ThicknessEditor, string> HeaderProperty =
-            AvaloniaProperty.RegisterDirect<ThicknessEditor, string>(nameof(Header), o => o.Header,
+        public static readonly DirectProperty<ThicknessEditor, string?> HeaderProperty =
+            AvaloniaProperty.RegisterDirect<ThicknessEditor, string?>(nameof(Header), o => o.Header,
                 (o, v) => o.Header = v);
 
         public static readonly DirectProperty<ThicknessEditor, bool> IsPresentProperty =
@@ -36,7 +36,7 @@ namespace Avalonia.Diagnostics.Controls
             AvaloniaProperty.Register<ThicknessEditor, IBrush>(nameof(Highlight));
 
         private Thickness _thickness;
-        private string _header;
+        private string? _header;
         private bool _isPresent = true;
         private double _left;
         private double _top;
@@ -50,7 +50,7 @@ namespace Avalonia.Diagnostics.Controls
             set => SetAndRaise(ThicknessProperty, ref _thickness, value);
         }
 
-        public string Header
+        public string? Header
         {
             get => _header;
             set => SetAndRaise(HeaderProperty, ref _header, value);