Make some members internal in core classes.

src/Avalonia.Base/StyledElement.cs

@@ -556,7 +556,7 @@ namespace Avalonia
         /// Notifies child controls that a change has been made to resources that apply to them.
         /// </summary>
         /// <param name="e">The event args.</param>
-        protected virtual void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
+        internal virtual void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
         {
             if (_logicalChildren is object)
             {

src/Avalonia.Base/Visual.cs

@@ -321,7 +321,7 @@ namespace Avalonia
 
         internal RenderOptions RenderOptions { get; set; }
 
-        public bool HasNonUniformZIndexChildren { get; private set; }
+        internal bool HasNonUniformZIndexChildren { get; private set; }
 
         /// <summary>
         /// Gets a value indicating whether this control is attached to a visual root.

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -318,7 +318,7 @@ namespace Avalonia.Controls.Primitives
         }
 
         /// <inheritdoc />
-        protected sealed override void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
+        internal sealed override void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
         {
             var count = VisualChildren.Count;
 

src/Avalonia.Controls/Primitives/VisualLayerManager.cs

@@ -104,7 +104,7 @@ namespace Avalonia.Controls.Primitives
         }
 
         /// <inheritdoc />
-        protected override void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
+        internal override void NotifyChildResourcesChanged(ResourcesChangedEventArgs e)
         {
             foreach (var l in _layers)
                 ((ILogical)l).NotifyResourcesChanged(e);