Shorthand for empty content.

	// Draws a button without any text.
	function OnGUI () {
		GUI.Button (Rect (0, 0, 100, 20), GUIContent.none);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnGUI() {
        GUI.Button(new Rect(0, 0, 100, 20), GUIContent.none);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnGUI() as void:
		GUI.Button(Rect(0, 0, 100, 20), GUIContent.none)