Calling script when completed field in *EDITOR*

I realize this may be super simple, but I’m actually working inside of a Custom List, so I have a Keycode, a Button and two string fields inside of my List, what I want to do is when I finish typing in my last string field, I want to run a script. Any ideas? Thank you! (:

Here is how my code is setup currently - What I need help with is how to get my current focus in the -Editor- then get the string value from this.

using UnityEngine;
using System.Collections;
using UnityEditor;
using System.Collections.Generic;
using UnityEngine.UI;

[CustomEditor(typeof(InputManager))]
public class InputManagerEditor : Editor {

	public override void OnInspectorGUI()
	{

		serializedObject.Update ();
		InputManager myTarget = (InputManager)target;

		EditorGUILayout.PropertyField(serializedObject.FindProperty("inputManagerList"), true);

		if(!GUI.GetNameOfFocusedControl().Equals("") && Event.current.keyCode == KeyCode.Return)
			TagEditor.AddToTagMenu(GUI.GetNameOfFocusedControl().ToString());

		serializedObject.ApplyModifiedProperties();

	}

}

You can probably do a check to see what control is focused and if the field is no longer empty. Simple example, but for a starting point, try something like this:

 /*pseudo*/
 if (lastFocusedControl == myInputField && myInputField != string.empty)  {
      //Call your script
 }

http://docs.unity3d.com/ScriptReference/GUI-changed.html

http://docs.unity3d.com/ScriptReference/GUI.FocusControl.html