// Tints with yellow the letters of the button.
function OnGUI() {
    GUI.contentColor = Color.yellow;
    GUI.Button(Rect(10,10,70,30), "A button");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnGUI() {
        GUI.contentColor = Color.yellow;
        GUI.Button(new Rect(10, 10, 70, 30), "A button");
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnGUI():
        GUI.contentColor = Color.yellow
        GUI.Button(Rect(10, 10, 70, 30), 'A button')