GUILayout.EndVertical  

function OnGUI () {
GUILayout.BeginVertical ("box");

GUILayout.Button ("I'm the top button");
GUILayout.Button ("I'm the bottom button");

// End the vertical group we started above
GUILayout.EndVertical();
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void OnGUI() {
GUILayout.BeginVertical("box");
GUILayout.Button("I'm the top button");
GUILayout.Button("I'm the bottom button");
GUILayout.EndVertical();
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def OnGUI():
GUILayout.BeginVertical('box')
GUILayout.Button('I\'m the top button')
GUILayout.Button('I\'m the bottom button')
GUILayout.EndVertical()