OverGUI

	void OnGUI () {
		if (sliderRect.Contains (Event.current.mousePosition)) {
//		if (sliderRect.Contains (Input.mousePosition)) {
			overGUI = true;
		} else {
			overGUI = false;
		}
	}

	void Update () {
		if (!overGUI) {
			DoSomething ();
		}
	}