Small Unity 3D Editor Extension that shows current editor state (Editing/Compiling/Paused/Updating). In order to use this script, just put it in Editor folder. Screenshot: http://goo.gl/VJukpV

EditorStateWindow.cs

using System;
using UnityEditor;
using UnityEngine;

namespace Nravo.Editors.Utils {

  public class EditorStateWindow : EditorWindow {
    static string _currentState = "";
    static GUIStyle _lableStyle = new GUIStyle();

    [MenuItem("Window/Editor State")]
    public static void ShowWindow() {
      EditorWindow.GetWindow<EditorStateWindow>(false, "----", true);
    }

    void OnEnable() {
      _lableStyle.fontSize = 24;
      _lableStyle.alignment = TextAnchor.MiddleCenter;
      _lableStyle.padding = new RectOffset(10, 10, 10, 10);
      _lableStyle.normal.textColor = Color.gray;
    }

    void OnGUI() {
      GUILayout.Space(36f);
      EditorGUILayout.LabelField(_currentState, _lableStyle);
    }

    void Update() {
      _currentState = GetCurrentState();
      this.title = _currentState;
      Repaint();
    }

    string GetCurrentState() {
      var state = "Editing";
      _lableStyle.normal.textColor = Color.gray;

      if(EditorApplication.isCompiling) {
        state = "Compiling";
        _lableStyle.normal.textColor = Color.red;
      } else if(EditorApplication.isPaused) {
        state = "Paused";
        _lableStyle.normal.textColor = Color.yellow;
      } else if(EditorApplication.isPlaying) {
        state = "Playing";
        _lableStyle.normal.textColor = Color.green;
      } else if(EditorApplication.isUpdating) {
        state = "Updating";
        _lableStyle.normal.textColor = Color.gray;
      } 

      return state;
    }
  }
}