Selection History for Unity Editor

SelectionHistory.cs

using UnityEditor;
using System.Collections.Generic;

public static class SelectionHistory {
	private const string PREV_SELECTED_MENU = "Edit/Previous Selection %&LEFT";
	private const string NEXT_SELECTED_MENU = "Edit/Next Selection %&RIGHT";
	private const int SELECTION_HISTORY_MENU_PRIORITY = 200;
	private const int MAX_HISTORY_COUNT = 10;

	private static readonly LinkedList<int[]> prevSelected = new LinkedList<int[]>();
	private static readonly Stack<int[]> nextSelected = new Stack<int[]>();
	private static int[] currentSelected;

	static SelectionHistory() {
		currentSelected = Selection.instanceIDs;
		Selection.selectionChanged += OnSelectionChanged;
	}

	private static void OnSelectionChanged() {
		int[] selected = Selection.instanceIDs;
		if (IsSelectionEquals(selected))
			return;
		if (currentSelected != null)
			prevSelected.AddLast(currentSelected);
		currentSelected = selected;
		nextSelected.Clear();
		while (prevSelected.Count > MAX_HISTORY_COUNT)
			prevSelected.RemoveFirst();
	}

	[MenuItem(PREV_SELECTED_MENU, true)]
	private static bool CheckPreviousSelectable() {
		return prevSelected.Count > 0;
	}

	[MenuItem(NEXT_SELECTED_MENU, true)]
	private static bool CheckNextSelectable() {
		return nextSelected.Count > 0;
	}

	[MenuItem(PREV_SELECTED_MENU, priority = SELECTION_HISTORY_MENU_PRIORITY)]
	public static void SelectPreviousSelected() {
		if (!CheckPreviousSelectable()) return;

		if (currentSelected != null)
			nextSelected.Push(currentSelected);
		currentSelected = prevSelected.Last.Value;
		prevSelected.RemoveLast();
		Selection.instanceIDs = currentSelected;
	}

	[MenuItem(NEXT_SELECTED_MENU, priority = SELECTION_HISTORY_MENU_PRIORITY)]
	public static void SelectNextSelected() {
		if (!CheckNextSelectable()) return;

		if (currentSelected != null)
			prevSelected.AddLast(currentSelected);
		currentSelected = nextSelected.Pop();
		Selection.instanceIDs = currentSelected;
	}

	private static bool IsSelectionEquals(int[] selected) {
		if (selected == currentSelected)
			return true;
		if (selected == null || currentSelected == null)
			return false;
		if (selected.Length != currentSelected.Length)
			return false;
		for (int i = 0; i < selected.Length; i++)
			if (currentSelected[i] != selected[i])
				return false;
		return true;
	}
}

Similar to undo/redo, but will not affect modified changes, only for selections.
Usage: drop this file to editor/ folder, and it is ready to use.

Hotkeys:
Ctrl + Alt + ← : Previous Selection
Ctrl + Alt + → : Next Selection