public Button(CCLayer layer)
{
// Give it a default texture, may get changed in ButtonStyle
sprite = new CCSprite ("ui/buttonup.png");
sprite.IsAntialiased = false;
this.AddChild (sprite);
label = new CCLabel("", "fonts/Aldrich-Regular.ttf", 24, CCLabelFormat.SystemFont);
label.IsAntialiased = false;
this.AddChild (label);
var touchListener = new CCEventListenerTouchAllAtOnce ();
touchListener.OnTouchesBegan = HandleTouchesBegan;
layer.AddEventListener (touchListener);
}