Show bool as button at right place

Hello community!
I want to display my bool variable in inspector as button, but in right place.
I have reached some kind of solution below, but it's draw my button at the bottom of the inspector...

Code (CSharp):

1.  
2.  
3.     public override void OnInspectorGUI()
4.     {
5.  
6.         SpawnManager spawnManager = target as SpawnManager;
7.         base.OnInspectorGUI();
8.         if (GUILayout.Button("RefreshModifiersSpawn"))
9.             spawnManager.RefreshModifiersSpawn = !spawnManager.RefreshModifiersSpawn;
10.      }
11.  

P.S. at the picture, red rectangle - desired place for my button.