GUIStyleState.background

Description

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

See also: scaledBackgrounds.

using UnityEngine;

public class Example : MonoBehaviour
{
    // Assigns a texture to customStyles[0] for when the control
    // is pressed down

    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;
        }
    }
}