// Modifies only the box style of the current GUISkin

var style : GUIStyle;

function OnGUI() {
GUI.skin.box = style;
GUILayout.Box("This is a box.");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
public GUIStyle style;
void OnGUI() {
GUI.skin.box = style;
GUILayout.Box("This is a box.");
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

public style as GUIStyle

def OnGUI():
GUI.skin.box = style
GUILayout.Box('This is a box.')