// Prints the left, right, top and down values of the GUIStyle margin
    private var rctOff : RectOffset;
    function OnGUI() {
        if(GUI.skin.customStyles.Length > 0) {
            rctOff = GUI.skin.customStyles[0].margin;
            Debug.Log("Left: " + rctOff.left + " Right: " + rctOff.right);
            Debug.Log("Top: " + rctOff.top + " Bottom: " + rctOff.bottom);
        }
    }

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    private RectOffset rctOff;
    void OnGUI() {
        if (GUI.skin.customStyles.Length > 0) {
            rctOff = GUI.skin.customStyles[0].margin;
            Debug.Log("Left: " + rctOff.left + " Right: " + rctOff.right);
            Debug.Log("Top: " + rctOff.top + " Bottom: " + rctOff.bottom);
        }
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    private rctOff as RectOffset

    def OnGUI():
        if GUI.skin.customStyles.Length > 0:
            rctOff = GUI.skin.customStyles[0].margin
            Debug.Log(((('Left: ' + rctOff.left) + ' Right: ') + rctOff.right))
            Debug.Log(((('Top: ' + rctOff.top) + ' Bottom: ') + rctOff.bottom))