etc

src/Avalonia.Controls/Control.cs

@@ -200,7 +200,6 @@ namespace Avalonia.Controls
         {
             base.OnAttachedToVisualTreeCore(e);
 
-            InvalidateFlowDirection();
             InitializeIfNeeded();
         }
 
@@ -210,6 +209,14 @@ namespace Avalonia.Controls
             base.OnDetachedFromVisualTreeCore(e);
         }
 
+        /// <inheritdoc/>
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+
+            InvalidateFlowDirection();
+        }
+
         /// <inheritdoc/>
         protected override void OnGotFocus(GotFocusEventArgs e)
         {

src/Avalonia.Visuals/Rendering/ImmediateRenderer.cs

@@ -285,6 +285,12 @@ namespace Avalonia.Rendering
                     renderTransform = (-offset) * visual.RenderTransform.Value * (offset);
                 }
 
+                if (visual.IsMirrorTransform)
+                {
+                    var mirrorMatrix = new Matrix(-1.0, 0.0, 0.0, 1.0, visual.Bounds.Width, 0);
+                    renderTransform *= mirrorMatrix;
+                }
+
                 m = renderTransform * m;
 
                 if (clipToBounds)