button drawn last not triggered

Hi folks,

I have a tricky situation where I want a button to be over another. Like a smaller button drawn on top of a bigger button.

I have the following code in my OnGUI function, the small button is never pressed.

 if (GUI.Button (Rect (0,360,100,100), "BIG")) {
         Debug.Log("BIG Button");
     }
     if (GUI.Button (Rect (0,360,50,50), "small")) {
         Debug.Log("Small Button");
     }

I've been playing with GUI.depth, nothing does to it.