public override void OnInspectorGUI()
    {
        base.DrawDefaultInspector();

        TerrainManager myTerrainManager = (TerrainManager)target;

        if (GUILayout.Button("Preview Terrain"))
        {
            myTerrainManager.PreviewTerrain();
        }
        if (GUILayout.Button("Clear"))
        {
            myTerrainManager.Clear();
        }
    }