Declare interface these already support

Terminal.Gui/Drawing/Attribute.cs

@@ -1,4 +1,5 @@
 #nullable enable
+using System.Numerics;
 using System.Text.Json.Serialization;
 
 namespace Terminal.Gui;
@@ -10,7 +11,7 @@ namespace Terminal.Gui;
 ///     <see cref="ColorScheme"/> class to define color schemes that can be used in an application.
 /// </remarks>
 [JsonConverter (typeof (AttributeJsonConverter))]
-public readonly struct Attribute : IEquatable<Attribute>
+public readonly struct Attribute : IEquatable<Attribute>, IEqualityOperators<Attribute, Attribute, bool>
 {
     /// <summary>Default empty attribute.</summary>
     public static readonly Attribute Default = new (Color.White, ColorName.Black);

Terminal.Gui/Drawing/ColorScheme.cs

@@ -1,5 +1,6 @@
 #nullable enable
 using System.Globalization;
+using System.Numerics;
 using System.Text.Json.Serialization;
 
 namespace Terminal.Gui;
@@ -13,7 +14,7 @@ namespace Terminal.Gui;
 ///     </para>
 /// </remarks>
 [JsonConverter (typeof (ColorSchemeJsonConverter))]
-public class ColorScheme : IEquatable<ColorScheme>
+public class ColorScheme : IEquatable<ColorScheme>, IEqualityOperators<ColorScheme, ColorScheme, bool>
 {
     private readonly Attribute _disabled;
     private readonly Attribute _focus;