GUIStyleState.background

Description

The background image used by GUI elements in this given state.

See also: scaledBackgrounds.

    // Assigns a texture to customStyles[0] for when the control
    // is pressed down

    var aTexture : Texture2D;

    function OnGUI() {
        if(!aTexture) {
            Debug.LogError("Assign a texture on the editor first");
            return;
        }
        if(GUI.skin.customStyles.Length > 0)
            GUI.skin.customStyles[0].active.background = aTexture;
    }

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;
        }
        if (GUI.skin.customStyles.Length > 0)
            GUI.skin.customStyles[0].active.background = aTexture;
        
    }
}