Space from the edge of GUIStyle to the start of the contents.

	// Prints the left, right, top and down values of the GUIStyle padding
	private var rctOff : RectOffset;
	function OnGUI() {
		rctOff = GUI.skin.button.padding;
		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() {
        rctOff = GUI.skin.button.padding;
        Debug.Log("Left: " + rctOff.left + " Right: " + rctOff.right);
        Debug.Log("Top: " + rctOff.top + " Bottom: " + rctOff.bottom);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	private rctOff as RectOffset

	def OnGUI() as void:
		rctOff = GUI.skin.button.padding
		Debug.Log(((('Left: ' + rctOff.left) + ' Right: ') + rctOff.right))
		Debug.Log(((('Top: ' + rctOff.top) + ' Bottom: ') + rctOff.bottom))