* Updated: event.preventDefault() has been added to all Mouse event handlers.

* Updated: Sprite.deltaX/Y removed due to non-use. prevX/Y values moved to Sprite._cache.prevX/Y.
* Updated: Due to missing extends parameter the Sprite prototype was picking up functions from classes it never meant to (Button, TilemapLayer), now fully isolated.

src/gameobjects/Button.js

@@ -186,7 +186,8 @@ Phaser.Button = function (game, x, y, key, callback, callbackContext, overFrame,
 
 };
 
-Phaser.Button.prototype = Phaser.Utils.extend(true, Phaser.Sprite.prototype, PIXI.Sprite.prototype);
+Phaser.Button.prototype = Object.create(Phaser.Sprite.prototype);
+Phaser.Button.prototype = Phaser.Utils.extend(true, Phaser.Button.prototype, Phaser.Sprite.prototype, PIXI.Sprite.prototype);
 Phaser.Button.prototype.constructor = Phaser.Button;
 
 /**