Dispose of Win32 GDI handles when TrayIcon closed (#19583)

src/Windows/Avalonia.Win32/TrayIconImpl.cs

@@ -274,10 +274,11 @@ namespace Avalonia.Win32
         private class TrayPopupRoot : Window
         {
             private readonly ManagedPopupPositioner _positioner;
-
+            private readonly TrayIconManagedPopupPositionerPopupImplHelper _positionerHelper;
             public TrayPopupRoot()
             {
-                _positioner = new ManagedPopupPositioner(new TrayIconManagedPopupPositionerPopupImplHelper(MoveResize));
+                _positionerHelper = new TrayIconManagedPopupPositionerPopupImplHelper(MoveResize);
+                _positioner = new ManagedPopupPositioner(_positionerHelper);
                 Topmost = true;
 
                 Deactivated += TrayPopupRoot_Deactivated;
@@ -292,6 +293,12 @@ namespace Avalonia.Win32
                 Close();
             }
 
+            protected override void OnClosed(EventArgs e)
+            {
+                base.OnClosed(e);
+                _positionerHelper.Dispose();
+            }
+
             private void MoveResize(PixelPoint position, Size size, double scaling)
             {
                 if (PlatformImpl is { } platformImpl)
@@ -315,7 +322,7 @@ namespace Avalonia.Win32
                 });
             }
 
-            private class TrayIconManagedPopupPositionerPopupImplHelper : IManagedPopupPositionerPopup
+            private class TrayIconManagedPopupPositionerPopupImplHelper : IManagedPopupPositionerPopup, IDisposable
             {
                 private readonly Action<PixelPoint, Size, double> _moveResize;
                 private readonly Window _hiddenWindow;
@@ -350,6 +357,11 @@ namespace Avalonia.Win32
                     _moveResize(new PixelPoint((int)devicePoint.X, (int)devicePoint.Y), virtualSize, Scaling);
                 }
 
+                public void Dispose()
+                {
+                    _hiddenWindow.Close();
+                }
+
                 public double Scaling => _hiddenWindow.Screens.Primary?.Scaling ?? 1.0;
             }
         }