Bone Animations

Hi, guys!
since the cocos2d-x 2.0.3 support bone Animations, i would like to do something about it.
now , i have a trouble about the demo.
in the CocosBuilderTest Animations of the demo, i found the grossini can run a loop action of the Idle,but i don’t konw where did it realized in the code.
then i check out the TestAnimations.ccb in the CocosBuilder, but also can’t found something about why the grossini run the “Idle” loop and loop,i did’t clicked the “Idle” Button.
so, i would like to know how to control the bone Animations as the Frame Animations, how to change body of the bone dynamically in my code, and how to get the CallBack of start Animation and end Animation. Can’t i controll the bone Animations just as the frame Animations? And i found the CCBAnimationsManager would be to improve so that i can use it to do more things about the bone Animations.
plsase help me!

Is anyone can help me?