Initialize EffectiveValue with inherited value.

Fixes #10345

src/Avalonia.Base/PropertyStore/EffectiveValue`1.cs

@@ -19,13 +19,16 @@ namespace Avalonia.PropertyStore
         private T? _baseValue;
         private UncommonFields? _uncommon;
 
-        public EffectiveValue(AvaloniaObject owner, StyledProperty<T> property)
+        public EffectiveValue(
+            AvaloniaObject owner,
+            StyledProperty<T> property,
+            EffectiveValue<T>? inherited)
         {
             Priority = BindingPriority.Unset;
             BasePriority = BindingPriority.Unset;
             _metadata = property.GetMetadata(owner.GetType());
 
-            var value = _metadata.DefaultValue;
+            var value = inherited is null ? _metadata.DefaultValue : inherited.Value;
 
             if (property.HasCoercion && _metadata.CoerceValue is { } coerce)
             {

src/Avalonia.Base/PropertyStore/ValueStore.cs

@@ -184,7 +184,7 @@ namespace Avalonia.PropertyStore
                 }
                 else
                 {
-                    var effectiveValue = new EffectiveValue<T>(Owner, property);
+                    var effectiveValue = CreateEffectiveValue(property);
                     AddEffectiveValue(property, effectiveValue);
                     effectiveValue.SetAndRaise(this, result, priority);
                 }
@@ -200,7 +200,7 @@ namespace Avalonia.PropertyStore
                 }
                 else
                 {
-                    var effectiveValue = new EffectiveValue<T>(Owner, property);
+                    var effectiveValue = CreateEffectiveValue(property);
                     AddEffectiveValue(property, effectiveValue);
                     effectiveValue.SetLocalValueAndRaise(this, property, value);
                 }
@@ -217,7 +217,7 @@ namespace Avalonia.PropertyStore
             }
             else
             {
-                var effectiveValue = new EffectiveValue<T>(Owner, property);
+                var effectiveValue = CreateEffectiveValue(property);
                 AddEffectiveValue(property, effectiveValue);
                 effectiveValue.SetCurrentValueAndRaise(this, property, value);
             }
@@ -287,6 +287,16 @@ namespace Avalonia.PropertyStore
             return false;
         }
 
+        public EffectiveValue<T> CreateEffectiveValue<T>(StyledProperty<T> property)
+        {
+            EffectiveValue<T>? inherited = null;
+
+            if (property.Inherits && TryGetInheritedValue(property, out var v))
+                inherited = (EffectiveValue<T>)v;
+
+            return new EffectiveValue<T>(Owner, property, inherited);
+        }
+
         public void SetInheritanceParent(AvaloniaObject? newParent)
         {
             var values = AvaloniaPropertyDictionaryPool<OldNewValue>.Get();

src/Avalonia.Base/StyledProperty.cs

@@ -171,7 +171,7 @@ namespace Avalonia
 
         internal override EffectiveValue CreateEffectiveValue(AvaloniaObject o)
         {
-            return new EffectiveValue<TValue>(o, this);
+            return o.GetValueStore().CreateEffectiveValue(this);
         }
 
         /// <inheritdoc/>