Remembers last button in Unity (keeps UI focused when you click off using mouse)

RememberLastButton.cs

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class RememberLastButton : MonoBehaviour
{
    GameObject lastSelected;

private void Update()
{
    
    if(EventSystem.current.currentSelectedGameObject == null)
    {
        if (lastSelected && lastSelected.gameObject.activeSelf && lastSelected.GetComponent<Button>() != null && lastSelected.GetComponent<Button>().interactable)
        {
            EventSystem.current.SetSelectedGameObject(lastSelected);
        }            
    }
    else
    {
        lastSelected = EventSystem.current.currentSelectedGameObject;
    }

    
}
}