Go back to previously selected object

GoBackSelection.cs

    [InitializeOnLoad]
    public static class GoBackSelection
    {
        static GoBackSelection()
        {
            Selection.selectionChanged -= HandleSelectionChange;
            Selection.selectionChanged += HandleSelectionChange;
            HandleSelectionChange();
        }

        private static Stack<UnityEngine.Object> stack = new Stack<UnityEngine.Object>();
        private static bool IgnoreSelection;

        private static void HandleSelectionChange()
        {
            if(IgnoreSelection)
            {
                IgnoreSelection = false; 
                return;
            }
            stack.Push(Selection.activeObject); 
        }

        [MenuItem("Edit/GoBack")]
        public static void GoBackMenuItem()
        {
            GoBack(); 
        }

        public static void GoBack()
        {
            if (stack.Count == 0) 
            {
                return;
            }

            if(stack.Count == 1)
            {
                var obj = stack.Peek();
                if(obj != Selection.activeObject)
                {
                    IgnoreSelection = true;
                    Selection.activeObject = stack.Peek();
                }
            }
            else
            {
                stack.Pop();
                var obj = stack.Peek();

                if (obj && obj != Selection.activeObject)
                {
                    IgnoreSelection = true;
                    Selection.activeObject = obj;
                }
            }
            
        }
    }