Enable compositing renderer by default for desktop platforms

samples/ControlCatalog.NetCore/Program.cs

@@ -113,13 +113,11 @@ namespace ControlCatalog.NetCore
                 {
                     EnableMultiTouch = true,
                     UseDBusMenu = true,
-                    EnableIme = true,
-                    UseCompositor = true
+                    EnableIme = true
                 })
                 .With(new Win32PlatformOptions
                 {
-                    EnableMultitouch = true,
-                    UseCompositor = true
+                    EnableMultitouch = true
                 })
                 .UseSkia()
                 .AfterSetup(builder =>

src/Avalonia.X11/X11Platform.cs

@@ -235,8 +235,8 @@ namespace Avalonia
         /// Immediate re-renders the whole scene when some element is changed on the scene. Deferred re-renders only changed elements.
         /// </remarks>
         public bool UseDeferredRendering { get; set; } = true;
-        
-        public bool UseCompositor { get; set; }
+
+        public bool UseCompositor { get; set; } = true;
 
         /// <summary>
         /// Determines whether to use IME.

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -49,8 +49,8 @@ namespace Avalonia
         /// Immediate re-renders the whole scene when some element is changed on the scene. Deferred re-renders only changed elements.
         /// </remarks>
         public bool UseDeferredRendering { get; set; } = true;
-        
-        public bool UseCompositor { get; set; }
+
+        public bool UseCompositor { get; set; } = true;
 
         /// <summary>
         /// Enables ANGLE for Windows. For every Windows version that is above Windows 7, the default is true otherwise it's false.