GUIStyle.active

public GUIStyleState active ;

Description

Отображает настройки когда кнопка нажата.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public Texture2D aTexture;
    void OnGUI() {
        if (!aTexture) {
            Debug.LogError("Assign a texture on the editor first");
            return;
        }
        GUI.skin.button.active.background = aTexture;
    }
}