We want to use the category names as labels for a set of tabs in the Palette window. When we select one of these tabs, only the level piece prefabs of the selected category will be displayed.

We will create a method called GetListFromEnum. This will help us to easily list enums for further use. Let's add this method inside the EditorUtils class:

public static List<T> GetListFromEnum<T> () {
    List<T> enumList = new List<T> ();
    System.Array enums = System.Enum.GetValues (typeof(T));
    foreach (T e in enums) { 
        enumList.Add (e);
    }
    return enumList;
}

The method receives an enum type as a generic type and returns a list with all the enum values in it.

Now, to create the GUI for the tabs, we need to make a few updates in the PaletteWindow.cs script, as follows:

using UnityEngine;
using UnityEditor;
using System.Collections...