Voxeland build progress in Unity Hierarchy

VoxelandHierarchyView.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UnityEditor;
using UnityEngine;

using Voxeland5;
/// <summary>
/// jasoncg
/// 2018-08-11
/// Based on 
/// https://gist.github.com/ilkinulas/802c993bb6bcdb3a45bfbdd01c2f3718
/// </summary>
[InitializeOnLoad]
public class VoxelandHierarchyView {
    static VoxelandHierarchyView() {
        EditorApplication.hierarchyChanged += EditorApplication_hierarchyChanged;
        EditorApplication.hierarchyWindowItemOnGUI += HierarchyWindowItemOnGUI;
    }

    private static void EditorApplication_hierarchyChanged () {
        RemoveStale();
    }

    private static Dictionary<GameObject, Voxeland> _voxelandObjects = new Dictionary<GameObject, Voxeland>();
    private static List<GameObject> temp = new List<GameObject>();
    private static void RemoveStale() {
        temp.AddRange(_voxelandObjects.Keys);
        foreach(var key in temp) {
            if(key == null)
                _voxelandObjects.Remove(key);
        }
        temp.Clear();
    }
    private static void HierarchyWindowItemOnGUI (int instanceID, Rect selectionRect) {
        GameObject gameObject = EditorUtility.InstanceIDToObject(instanceID) as GameObject;
        if(gameObject == null)
            return;
        Voxeland voxeland = null;
        if(!_voxelandObjects.TryGetValue(gameObject, out voxeland)) { 
            _voxelandObjects[gameObject] = gameObject.GetComponent<Voxeland>();
        }
        if(voxeland == null)
            return;
        Rect r = new Rect(selectionRect);
        float areaWidth = Mathf.Min(240, r.width*0.75f);
        r.x += r.width - areaWidth;

        if(ThreadWorker.IsWorking("Voxeland")) {
            //Rect r = new Rect(selectionRect);
            float calculatedSum; float completeSum; float totalSum;
            ThreadWorker.GetProgresByTag("VoxelandChunk", out totalSum, out calculatedSum, out completeSum);
            if(totalSum > 0) {
                GUI.Label(r, $"Building ({(calculatedSum / totalSum)}) ({(completeSum / totalSum)})");
                var calculated = (calculatedSum / totalSum);
                var complete = (completeSum / totalSum);

                r.width = areaWidth; // / 2.0f;

                EditorGUI.ProgressBar(r, complete, $"{completeSum} / {totalSum}");
                EditorApplication.RepaintHierarchyWindow();
            } else {
                GUI.Label(r, "Rebuilding...");
            }
        } else {

            r.width = areaWidth / 2.0f;

            if(GUI.Button(r, "Rebuild")) {
                voxeland.Rebuild();
            }
            r.x += areaWidth / 2.0f;
            //r.width = areaWidth-r.x;
            if(GUI.Button(r, "Force Generate")) {
                voxeland.Generate(true);
            }
        }
    }
}