WinUI Comp tweak backdrop blur.

src/Windows/Avalonia.Win32/Composition/CompositionConnector.cs

@@ -127,17 +127,13 @@ namespace Avalonia.Win32
         private SpriteVisual CreateBlur()
         {
             var blurEffect = new GaussianBlurEffect(new CompositionEffectSourceParameter("backdrop"));
-            var blurEffectFactory = _compositor.CreateEffectFactory(blurEffect);
 
-            var blurBrush = blurEffectFactory.CreateBrush();
             var backDropBrush = _compositor.CreateBackdropBrush();
 
-            blurBrush.SetSourceParameter("backdrop", backDropBrush);
-
             var saturateEffect = new SaturationEffect(blurEffect);
             var satEffectFactory = _compositor.CreateEffectFactory(saturateEffect);
-
             var satBrush = satEffectFactory.CreateBrush();
+            
             satBrush.SetSourceParameter("backdrop", backDropBrush);
 
             var visual = _compositor.CreateSpriteVisual();

src/Windows/Avalonia.Win32/Composition/SaturationEffect.cs

@@ -6,7 +6,7 @@ namespace Avalonia.Win32
 {
     class SaturationEffect : EffectBase
     {
-        public SaturationEffect(IGraphicsEffect source) : base(source)
+        public SaturationEffect(IGraphicsEffectSource source) : base(source)
         {
         }