Canvas 水滴

双击可以把水滴分离；拖放到一起可以融合；
晃动浏览器可以让水滴跳动；键盘左右键可以切换皮肤；上下键可以变换大小。
Shake the browser window to make them bounce.
Use the keyboard up / down arrows to change blob size and
the left / right arrows to change between skins.