Base work on SceneView Toolbar

Editor/GameViewLink/LinkGameView.cs

 
 namespace GameplayIngredients.Editor
 {
-    static class LinkGameView
+    public static class LinkGameView
-        static bool Active
+        public static bool Active
         {
             get
             {

Editor/SceneViewToolbar.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEditor;
+using System;
+
+namespace GameplayIngredients.Editor
+{
+    static class SceneViewToolbar
+    {
+        [InitializeOnLoadMethod]
+        static void Initialize()
+        {
+            SceneView.onSceneGUIDelegate += OnSceneGUI;
+        }
+
+        private static void OnSceneGUI(SceneView sceneView)
+        {
+            var r = new Rect(Vector2.zero, new Vector2(sceneView.position.width,24));
+
+            using (new GUILayout.AreaScope(r))
+            {
+                using (new GUILayout.HorizontalScope(EditorStyles.toolbar))
+                {
+                    bool link = LinkGameView.Active;
+                    link = GUILayout.Toggle(link, "Link Game View", EditorStyles.toolbarButton);
+
+                    if (GUI.changed)
+                        LinkGameView.Active = link;
+
+                    GUILayout.FlexibleSpace();
+                }
+            }
+        }
+
+        static class Styles
+        {
+            public static GUIStyle toolbar;
+
+            static Styles()
+            {
+                toolbar = new GUIStyle(EditorStyles.inspectorFullWidthMargins);                
+            }
+        }
+    }
+}
+

Editor/SceneViewToolbar.cs.meta

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