Why i don't see the button in the Inspector on debug mode ?

Button script:

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4. using UnityEditor;
5.  
6. [CustomEditor(typeof(LevelMap))]
7. public class CustomButton : Editor
8. {
9.     public override void OnInspectorGUI()
10.     {
11.         LevelMap Generate = (LevelMap)target;
12.         if (GUILayout.Button("Generate Map"))
13.         {
14.             Generate.GenerateNew();
15.         }
16.     }
17. }
18.  

And a script that is attached to a empty GameObject the Level Map:

Code (csharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5. using UnityEngine.UI;
6.  
7. [ExecuteInEditMode]
8. public class LevelMap : MonoBehaviour
9. {
10.     public GameObject Node;
11.     public Vector3 nodeSize;
12.     public int Rows;
13.     public int Columns;
14.     public int mapWidth;
15.     public int mapHeight;
16.     public float Spacing = 2.0f;
17.     public float spawnSpeed = 0;
18.  
19.     private void Start()
20.     {
21.  
22.         Generate();
23.     }
24.  
25.     private void Generate()
26.     {
27.         for (int x = 0; x < mapWidth; x++)
28.         {
29.             for (int z = 0; z < mapHeight; z++)
30.             {
31.                 GameObject block = Instantiate(Node, Vector3.zero, Node.transform.rotation) as GameObject;
32.                 block.transform.parent = transform;
33.                 block.transform.localPosition = new Vector3(x, 0, z);
34.             }
35.         }
36.     }
37.  
38.     public void GenerateNew()
39.     {
40.         Generate();
41.     }
42. }
43.  

One of the problems is that in the Inspector if the mode is normal i see the Generate Button. But i don't see the public variables of Level Map. If i change the mode to Debug then i will see the Level Map public variables but i will not see the button.

How can i make that i will see the button and the variables at the same mode ? (normal or debug)

Another problem is how can i make that if generated a new map now if i will change one or more of the variables values in the editor it will effect the GenerateMap in real time ? For example if i change the Spacing variable value if it was for example 2 and i change it to 4 then generate a new map but with spacing 4.

So the button is like for reset to generate whole new map but changing variables values will effect the current map only.

 

https://docs.unity3d.com/ScriptReference/Editor.DrawDefaultInspector.html

 

For the first problem i just added in the button script the line:

Code (csharp):

1.  
2. DrawDefaultInspector();
3.  

For the second problem if i'm not using Update and only Start() it will never effect in real time the map if i change any of the public variables values. Then how can i do it ?