CAMetalLayer should not be opaque (#14761)

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

@@ -112,6 +112,7 @@ public:
 - (MetalRenderTarget *)initWithDevice:(IAvnMetalDevice *)device {
     _device = dynamic_cast<AvnMetalDevice*>(device);
     _layer = [CAMetalLayer new];
+    _layer.opaque = false;
     _layer.device = _device->device;
     _target.setNoAddRef(new AvnMetalRenderTarget(_layer, _device));
     return self;
@@ -158,4 +159,4 @@ static AvnMetalDisplay* _display = new AvnMetalDisplay();
 extern IAvnMetalDisplay* GetMetalDisplay()
 {
     return _display;
-}
+}

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -98,6 +98,7 @@ namespace Avalonia.iOS
 #endif
             if (l is CAMetalLayer metalLayer)
             {
+                metalLayer.Opaque = false;
                 _topLevelImpl.Surfaces = new[] { new Metal.MetalPlatformSurface(metalLayer, this) };
             }
         }