Rolled Back fix

Editor/WelcomeScreen/WelcomeScreen.cs

         const int WindowWidth = 640;
         const int WindowHeight = 520;
 
-        static WelcomeScreen s_Instance;
-
         static bool showOnStartup
         {
             get { return EditorPrefs.GetBool(kShowOnStartupPreference, true); }
         [MenuItem("Window/Gameplay Ingredients")]
         static void ShowFromMenu()
         {
-            s_Instance = GetWindow<WelcomeScreen>(true, "Gameplay Ingredients");
+            GetWindow<WelcomeScreen>(true, "Gameplay Ingredients");
         }
 
         private void OnEnable()
                 wizardMode = WizardMode.FirstTimeSetup;
 
             InitTips();
-        }
-
-        private void OnDisable()
-        {
-            if (s_Instance != null)
-                s_Instance.Close();
         }
 
         private void OnDestroy()