MenuBase.cs

using System.Collections;
using System.Collections.Generic;

using UnityEngine;
using GameEventSystem;

public class MenuBase : MonoBehaviour {

    public void onEnterScreen()
    {
        // Do basic logic for opening
        preActive();
        InitScreen();
        Canvas aCanvas = gameObject.GetComponent<Canvas>();
        aCanvas.worldCamera = Camera.main;
        
        gameObject.SetActive(true);
        postActive();
    }

    public virtual void onExitScreen()
    {
        // Do basic logic for closing
        preDeactive();
        gameObject.SetActive(false);
    }

	public void ShowMenu(int menu, bool closePrivous = true)
    {
        Hashtable hashParams = new Hashtable();
        hashParams.Add(GameEventParam.SCREEN_TO_OPEN, menu);

        
        GameEventManager.TriggerEvent(GameEvents.E_OPEN_SCREEN, hashParams);
    }

	public virtual void InitScreen () {}
    public virtual void preActive  () {}
    public virtual void postActive () {}
    public virtual void preDeactive() {}
}