fix: ResourceExtensions throwing ArgumentException on windows (backport #1190)

src/Uno.Toolkit.UI/Behaviors/ResourceExtensions.cs

@@ -36,7 +36,11 @@ private static void OnResourcesChanged(DependencyObject d, DependencyPropertyCha
 		{
 			if (d is Control control && e.NewValue is ResourceDictionary newResources)
 			{
+#if !HAS_UNO
+				control.Resources = newResources.DeepClone();
+#else
 				control.Resources = newResources;
+#endif
 			}
 		}
 	}

src/Uno.Toolkit.UI/Extensions/ResourceDictionaryExtensions.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using Uno.Extensions;
+using Uno.Logging;
+
+#if IS_WINUI
+using Microsoft.UI.Xaml;
+#else
+using Windows.UI.Xaml;
+#endif
+
+namespace Uno.Toolkit.UI;
+
+internal static class ResourceDictionaryExtensions
+{
+	private static readonly ILogger _logger = typeof(ResourceDictionaryExtensions).Log();
+
+	/// <summary>
+	/// Creates a deep clone of the given <see cref="ResourceDictionary"/>.
+	/// </summary>
+	/// <param name="rd">The resource dictionary to clone.</param>
+	/// <returns>A deep clone of the resource dictionary.</returns>
+	/// <remarks>Only the resource dictionary, its nesting theme, and merged dictionaries are deep-cloned. Not their values.</remarks>
+	public static ResourceDictionary DeepClone(this ResourceDictionary rd)
+	{
+		try
+		{
+			if (rd.Source is not null) return new ResourceDictionary() { Source = rd.Source };
+
+			var result = new ResourceDictionary();
+
+			if (rd.ThemeDictionaries is { })
+			{
+				foreach (var (key, value) in rd.ThemeDictionaries)
+				{
+					result.ThemeDictionaries[key] = (value as ResourceDictionary)?.DeepClone() ?? value;
+				}
+			}
+			if (rd.MergedDictionaries is { })
+			{
+				foreach (var md in rd.MergedDictionaries)
+				{
+					result.MergedDictionaries.Add(md.DeepClone());
+				}
+			}
+			foreach (var (key, value) in rd)
+			{
+				result[key] = value;
+			}
+
+			return result;
+		}
+		catch (Exception e)
+		{
+			_logger.Error("Failed to clone the resource-dictionary", e);
+			throw;
+		}
+	}
+}