Respond to WM_CAPTURECHANGED (#19685)

* Respond to WM_CAPTURECHANGED

* Addressing PR feedback

---------

Co-authored-by: Jan Kučera <miloush@users.noreply.github.com>

src/Avalonia.Base/Input/MouseDevice.cs

@@ -104,6 +104,9 @@ namespace Avalonia.Input
                 case RawPointerEventType.Swipe:
                     e.Handled = GestureSwipe(mouse, e.Timestamp, e.Root, e.Position, props, ((RawPointerGestureEventArgs)e).Delta, keyModifiers, e.InputHitTestResult.firstEnabledAncestor);
                     break;
+                case RawPointerEventType.CancelCapture:
+                    PlatformCaptureLost();
+                    break;
             }
         }
 
@@ -308,7 +311,7 @@ namespace Avalonia.Input
 
         internal void PlatformCaptureLost()
         {
-            _pointer.Capture(null);
+            _pointer.PlatformCaptureLost();
         }
     }
 }

src/Avalonia.Base/Input/Pointer.cs

@@ -32,14 +32,28 @@ namespace Avalonia.Input
         {
             
         }
-        
+
+        internal void PlatformCaptureLost()
+        {
+            if (Captured != null)
+                Capture(null, platformInitiated: true);
+        }
+
         public void Capture(IInputElement? control)
+        {
+            Capture(control, platformInitiated: false);
+        }
+
+        private void Capture(IInputElement? control, bool platformInitiated)
         {
             if (Captured is Visual v1)
                 v1.DetachedFromVisualTree -= OnCaptureDetached;
             var oldCapture = Captured;
             Captured = control;
-            PlatformCapture(control);
+            
+            if (!platformInitiated)
+                PlatformCapture(control);
+
             if (oldCapture is Visual v2)
             {
                 var commonParent = FindCommonParent(control, oldCapture);

src/Avalonia.Base/Input/Raw/RawPointerEventArgs.cs

@@ -26,7 +26,8 @@ namespace Avalonia.Input.Raw
         TouchCancel,
         Magnify,
         Rotate,
-        Swipe
+        Swipe,
+        CancelCapture
     }
 
     /// <summary>

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

@@ -394,6 +394,26 @@ namespace Avalonia.Win32
                         break;
                     }
 
+                case WindowsMessage.WM_CAPTURECHANGED:
+                    {
+                        if (IsMouseInPointerEnabled)
+                        {
+                            break;
+                        }
+                        if (_hwnd != lParam)
+                        {
+                            _trackingMouse = false;
+                            e = new RawPointerEventArgs(
+                                _mouseDevice,
+                                timestamp,
+                                Owner,
+                                RawPointerEventType.CancelCapture,
+                                new Point(-1, -1),
+                                WindowsKeyboardDevice.Instance.Modifiers);
+                        }
+                        break;
+                    }
+
                 case WindowsMessage.WM_NCLBUTTONDOWN:
                 case WindowsMessage.WM_NCRBUTTONDOWN:
                 case WindowsMessage.WM_NCMBUTTONDOWN: